Add regression test for `const var`

Check that variables declared with `const var` can not be modified.

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

ivtest/ivltests/sv_const_fail9.v

@@ -0,0 +1,13 @@
+// Check that blocking assignment to a const variable fails, when the variable is
+// declared with the `var` keyword.
+
+module test;
+
+  const var integer x = 10;
+
+  initial begin
+    x = 20; // Error: Assignment to const variable
+    $display("FAILED");
+  end
+
+endmodule

ivtest/regress-vvp.list

@@ -73,6 +73,7 @@ sv_const_fail5			vvp_tests/sv_const_fail5.json
 sv_const_fail6			vvp_tests/sv_const_fail6.json
 sv_const_fail7			vvp_tests/sv_const_fail7.json
 sv_const_fail8			vvp_tests/sv_const_fail8.json
+sv_const_fail9			vvp_tests/sv_const_fail9.json
 sv_foreach9			vvp_tests/sv_foreach9.json
 sv_foreach10			vvp_tests/sv_foreach10.json
 sv_module_port1			vvp_tests/sv_module_port1.json

ivtest/vvp_tests/sv_const_fail9.json

@@ -0,0 +1,5 @@
+{
+    "type"          : "CE",
+    "source"        : "sv_const_fail9.v",
+    "iverilog-args" : [ "-g2005-sv" ]
+}