Add regression tests for `null` array dimensions

Check that source `null` expressions in `[null]` and `[null:N]` are
rejected rather than treated as the `$` marker for unbounded and bounded
queue dimensions.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>

ivtest/ivltests/sv_dimension_null_range_fail.v

@@ -0,0 +1,5 @@
+// Check that null is not confused with a bounded queue dimension.
+
+module test;
+  integer value[null:2];
+endmodule

ivtest/ivltests/sv_dimension_null_size_fail.v

@@ -0,0 +1,5 @@
+// Check that null is not confused with an unbounded queue dimension.
+
+module test;
+  integer value[null];
+endmodule

ivtest/regress-vvp.list

@@ -338,6 +338,8 @@ sv_declaration_after_null_statement_fail	vvp_tests/sv_declaration_after_null_sta
 sv_default_port_value1		vvp_tests/sv_default_port_value1.json
 sv_default_port_value2		vvp_tests/sv_default_port_value2.json
 sv_default_port_value3		vvp_tests/sv_default_port_value3.json
+sv_dimension_null_range_fail	vvp_tests/sv_dimension_null_range_fail.json
+sv_dimension_null_size_fail	vvp_tests/sv_dimension_null_size_fail.json
 sv_enum_reference_order	vvp_tests/sv_enum_reference_order.json
 sv_enum_reference_order_relaxed	vvp_tests/sv_enum_reference_order_relaxed.json
 sv_foreach9			vvp_tests/sv_foreach9.json

ivtest/vvp_tests/sv_dimension_null_range_fail.json

@@ -0,0 +1,5 @@
+{
+    "type"          : "CE",
+    "source"        : "sv_dimension_null_range_fail.v",
+    "iverilog-args" : [ "-g2005-sv" ]
+}

ivtest/vvp_tests/sv_dimension_null_size_fail.json

@@ -0,0 +1,5 @@
+{
+    "type"          : "CE",
+    "source"        : "sv_dimension_null_size_fail.v",
+    "iverilog-args" : [ "-g2005-sv" ]
+}