[testsuite] Run dg-final.exp sequentially

2018-06-15  Tom de Vries  <tdevries@suse.de>

	* gcc.dg-selftests/dg-final.exp: Force sequential execution.

From-SVN: r261643

gcc/testsuite/ChangeLog

+2018-06-15  Tom de Vries  <tdevries@suse.de>
+
+	* gcc.dg-selftests/dg-final.exp: Force sequential execution.
+
 2018-06-15  Nick Clifton  <nickc@redhat.com>
 
 	PR 84195

gcc/testsuite/gcc.dg-selftests/dg-final.exp

@@ -98,4 +98,9 @@ proc dg_final_directive_check_num_args {} {
     unset testname_with_flags
 }
 
+if ![gcc_parallel_test_run_p dg-final] {
+    return
+}
+gcc_parallel_test_enable 0
 dg_final_directive_check_num_args
+gcc_parallel_test_enable 1