Fix run-test-suite.pl with coverage
diff --git a/tests/scripts/run-test-suites.pl b/tests/scripts/run-test-suites.pl
index e8611f4..ab9db82 100644
--- a/tests/scripts/run-test-suites.pl
+++ b/tests/scripts/run-test-suites.pl
@@ -6,7 +6,7 @@
 use utf8;
 use open qw(:std utf8);
 
-my @suites = grep { ! /\.c$/ } glob 'test_suite_*';
+my @suites = grep { ! /\.(?:c|gcno)$/ } glob 'test_suite_*';
 die "$0: no test suite found\n" unless @suites;
 
 # in case test suites are linked dynamically