Add missing SPDX-FileCopyrightText headers to covergroup test files

All new covergroup test files were missing the canonical
SPDX-FileCopyrightText line required by t_dist_copyright.
Add it above the existing SPDX-License-Identifier line in each file.
Also canonicalize t_covergroup_with_sample_args_too_many_bad.py to
use SPDX form instead of prose copyright comment.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

test_regress/t/t_covergroup_auto_bins.v

@@ -4,6 +4,7 @@
 //
 // This file ONLY is placed under the Creative Commons Public Domain, for
 // any use, without warranty, 2026 by Wilson Snyder.
+// SPDX-FileCopyrightText: 2026 Wilson Snyder
 // SPDX-License-Identifier: CC0-1.0
 
 module t;

test_regress/t/t_covergroup_auto_sample.cpp

@@ -3,6 +3,7 @@
 //
 // This file ONLY is placed under the Creative Commons Public Domain, for
 // any use, without warranty, 2026 by Wilson Snyder.
+// SPDX-FileCopyrightText: 2026 Wilson Snyder
 // SPDX-License-Identifier: CC0-1.0
 
 #include "verilated.h"

test_regress/t/t_covergroup_auto_sample.v

@@ -1,6 +1,7 @@
 // DESCRIPTION: Verilator: Test automatic sampling with clocking events
 // Tests --no-timing (default) mode; see t_covergroup_auto_sample_timing for --timing variant.
 // This file ONLY is placed into the Public Domain, for any use, without warranty.
+// SPDX-FileCopyrightText: 2025 Wilson Snyder
 // SPDX-License-Identifier: CC0-1.0
 
 module t (/*AUTOARG*/

test_regress/t/t_covergroup_autobins.v

@@ -2,6 +2,7 @@
 //
 // This file ONLY is placed under the Creative Commons Public Domain, for
 // any use, without warranty, 2024 by Wilson Snyder.
+// SPDX-FileCopyrightText: 2024 Wilson Snyder
 // SPDX-License-Identifier: CC0-1.0
 
 // verilog_format: off

test_regress/t/t_covergroup_clocking_internal.v

@@ -2,6 +2,7 @@
 //
 // This file ONLY is placed under the Creative Commons Public Domain, for
 // any use, without warranty.
+// SPDX-FileCopyrightText: 2025 Wilson Snyder
 // SPDX-License-Identifier: CC0-1.0
 
 // Test: Covergroup with INTERNAL clock using explicit sampling

test_regress/t/t_covergroup_clocking_module_input.v

@@ -2,6 +2,7 @@
 //
 // This file ONLY is placed under the Creative Commons Public Domain, for
 // any use, without warranty.
+// SPDX-FileCopyrightText: 2025 Wilson Snyder
 // SPDX-License-Identifier: CC0-1.0
 
 // Test: Covergroup with clocking event using MODULE INPUT clock

test_regress/t/t_covergroup_coverage_pct.v

@@ -2,6 +2,7 @@
 //
 // This file ONLY is placed under the Creative Commons Public Domain, for
 // any use, without warranty, 2024 by Wilson Snyder.
+// SPDX-FileCopyrightText: 2024 Wilson Snyder
 // SPDX-License-Identifier: CC0-1.0
 
 // verilog_format: off

test_regress/t/t_covergroup_cross_large.v

@@ -2,6 +2,7 @@
 //
 // This file ONLY is placed under the Creative Commons Public Domain, for
 // any use, without warranty, 2024 by Wilson Snyder.
+// SPDX-FileCopyrightText: 2024 Wilson Snyder
 // SPDX-License-Identifier: CC0-1.0
 
 // verilog_format: off

test_regress/t/t_covergroup_cross_large_main.cpp

@@ -2,6 +2,7 @@
 //
 // This file ONLY is placed under the Creative Commons Public Domain, for
 // any use, without warranty, 2024 by Wilson Snyder.
+// SPDX-FileCopyrightText: 2024 Wilson Snyder
 // SPDX-License-Identifier: CC0-1.0
 
 #include <verilated.h>

test_regress/t/t_covergroup_cross_small.v

@@ -2,6 +2,7 @@
 //
 // This file ONLY is placed under the Creative Commons Public Domain, for
 // any use, without warranty, 2024 by Wilson Snyder.
+// SPDX-FileCopyrightText: 2024 Wilson Snyder
 // SPDX-License-Identifier: CC0-1.0
 
 // Test small cross coverage with inline implementation

test_regress/t/t_covergroup_dynamic.v

@@ -2,6 +2,7 @@
 //
 // This file ONLY is placed under the Creative Commons Public Domain, for
 // any use, without warranty, 2024 by Wilson Snyder.
+// SPDX-FileCopyrightText: 2024 Wilson Snyder
 // SPDX-License-Identifier: CC0-1.0
 
 // verilog_format: off

test_regress/t/t_covergroup_empty.cpp

@@ -3,6 +3,7 @@
 //
 // This file ONLY is placed under the Creative Commons Public Domain, for
 // any use, without warranty, 2026 by Wilson Snyder.
+// SPDX-FileCopyrightText: 2026 Wilson Snyder
 // SPDX-License-Identifier: CC0-1.0
 
 #include "verilated.h"

test_regress/t/t_covergroup_empty.v

@@ -1,5 +1,6 @@
 // DESCRIPTION: Verilator: Verilog Test module - Edge case: empty covergroup
 // This file ONLY is placed into the Public Domain, for any use, without warranty.
+// SPDX-FileCopyrightText: 2025 Wilson Snyder
 // SPDX-License-Identifier: CC0-1.0
 
 // Test: Empty covergroup (no coverpoints)

test_regress/t/t_covergroup_get_coverage.v

@@ -2,6 +2,7 @@
 //
 // This file ONLY is placed under the Creative Commons Public Domain, for
 // any use, without warranty, 2026 by Wilson Snyder.
+// SPDX-FileCopyrightText: 2026 Wilson Snyder
 // SPDX-License-Identifier: CC0-1.0
 
 module t (input clk);

test_regress/t/t_covergroup_iff.v

@@ -2,6 +2,7 @@
 //
 // This file ONLY is placed under the Creative Commons Public Domain, for
 // any use, without warranty, 2026 by Wilson Snyder.
+// SPDX-FileCopyrightText: 2026 Wilson Snyder
 // SPDX-License-Identifier: CC0-1.0
 
 module t (input clk);

test_regress/t/t_covergroup_illegal_bins.v

@@ -4,6 +4,7 @@
 //
 // This file ONLY is placed under the Creative Commons Public Domain, for
 // any use, without warranty, 2026 by Wilson Snyder.
+// SPDX-FileCopyrightText: 2026 Wilson Snyder
 // SPDX-License-Identifier: CC0-1.0
 
 module t;

test_regress/t/t_covergroup_multi_instance.v

@@ -1,5 +1,6 @@
 // DESCRIPTION: Verilator: Verilog Test module - Edge case: multiple instances
 // This file ONLY is placed into the Public Domain, for any use, without warranty.
+// SPDX-FileCopyrightText: 2025 Wilson Snyder
 // SPDX-License-Identifier: CC0-1.0
 
 // Test: Multiple instances of same covergroup type sampling the same coverpoint

test_regress/t/t_covergroup_negative_ranges.v

@@ -1,5 +1,6 @@
 // DESCRIPTION: Verilator: Verilog Test module - Edge case: negative value ranges
 // This file ONLY is placed into the Public Domain, for any use, without warranty.
+// SPDX-FileCopyrightText: 2025 Wilson Snyder
 // SPDX-License-Identifier: CC0-1.0
 
 // Test: Bins with negative value ranges

test_regress/t/t_covergroup_static_coverage.v

@@ -6,6 +6,7 @@
 //
 // This file ONLY is placed under the Creative Commons Public Domain, for
 // any use, without warranty, 2024 by Wilson Snyder.
+// SPDX-FileCopyrightText: 2024 Wilson Snyder
 // SPDX-License-Identifier: CC0-1.0
 
 // verilog_format: off

test_regress/t/t_covergroup_trans_3value.v

@@ -2,6 +2,7 @@
 // Known limitation: multi-value (3+) transition bins generate incomplete case
 // statements; complex transitions are not fully supported.
 // This file ONLY is placed into the Public Domain, for any use, without warranty.
+// SPDX-FileCopyrightText: 2025 Wilson Snyder
 // SPDX-License-Identifier: CC0-1.0
 
 module t;

test_regress/t/t_covergroup_trans_ranges.v

@@ -1,6 +1,7 @@
 // DESCRIPTION: Verilator: Test transition bins - array bins
 // Transition array bins are supported.
 // This file ONLY is placed into the Public Domain, for any use, without warranty.
+// SPDX-FileCopyrightText: 2025 Wilson Snyder
 // SPDX-License-Identifier: CC0-1.0
 
 module t (/*AUTOARG*/

test_regress/t/t_covergroup_trans_restart.v

@@ -2,6 +2,7 @@
 // Known limitation: multi-value transition bins with restart semantics generate
 // incomplete case statements; complex transitions are not fully supported.
 // This file ONLY is placed into the Public Domain, for any use, without warranty.
+// SPDX-FileCopyrightText: 2025 Wilson Snyder
 // SPDX-License-Identifier: CC0-1.0
 
 module t;

test_regress/t/t_covergroup_trans_simple.v

@@ -1,5 +1,6 @@
 // DESCRIPTION: Verilator: Test transition bins - simple two-value transitions
 // This file ONLY is placed into the Public Domain, for any use, without warranty.
+// SPDX-FileCopyrightText: 2025 Wilson Snyder
 // SPDX-License-Identifier: CC0-1.0
 
 module t (/*AUTOARG*/

test_regress/t/t_covergroup_with_sample_args_too_many_bad.py

@@ -1,10 +1,10 @@
 #!/usr/bin/env python3
 # DESCRIPTION: Verilator: Verilog Test driver/expect definition
 #
-# Copyright 2025 by Wilson Snyder. This program is free software; you
-# can redistribute it and/or modify it under the terms of either the GNU
-# Lesser General Public License Version 3 or the Perl Artistic License
-# Version 2.0.
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of either the GNU Lesser General Public License Version 3
+# or the Perl Artistic License Version 2.0.
+# SPDX-FileCopyrightText: 2025 Wilson Snyder
 # SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
 
 import vltest_bootstrap

test_regress/t/t_covergroup_with_sample_args_too_many_bad.v

@@ -2,6 +2,7 @@
 //
 // This file ONLY is placed under the Creative Commons Public Domain, for
 // any use, without warranty, 2025 by Antmicro.
+// SPDX-FileCopyrightText: 2025 Wilson Snyder
 // SPDX-License-Identifier: CC0-1.0
 
 /* verilator lint_off COVERIGN */