gtester: do not consider skipped tests as failures

This is happening since f591366eee, that
changed the way tests were skipped to use g_test_skip() instead of just
ignoring them. They are now reported to the log with G_TEST_RUN_SKIPPED
as result.

https://bugzilla.gnome.org/show_bug.cgi?id=790934

glib/gtestutils.c

@@ -731,12 +731,6 @@ static void     gtest_default_log_handler       (const gchar    *log_domain,
                                                  gpointer        unused_data);
 
 
-typedef enum {
-  G_TEST_RUN_SUCCESS,
-  G_TEST_RUN_SKIPPED,
-  G_TEST_RUN_FAILURE,
-  G_TEST_RUN_INCOMPLETE
-} GTestResult;
 static const char * const g_test_result_names[] = {
   "OK",
   "SKIP",