Tests: Skip t_constraint_state when no solver is installed (#5224)

test_regress/t/t_constraint_state.pl

@@ -10,13 +10,16 @@ if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); di
 
 scenarios(simulator => 1);
 
-compile(
+if (!$Self->have_solver) {
+    skip("No constraint solver installed");
+} else {
+    compile(
         );
 
-execute(
+    execute(
         check_finished => 1,
         );
-
+}
 
 ok(1);
 1;