selftest: sync: merge tests for sw_sync framework

These tests are based on the libsync test suite from Android.
This commit includes tests for basic merge operations.

Signed-off-by: Emilio López <emilio.lopez@collabora.co.uk>
Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>

tools/testing/selftests/sync/sync_test.c

@@ -64,6 +64,7 @@ int main(void)
 
 	err += RUN_TEST(test_fence_one_timeline_wait);
 	err += RUN_TEST(test_fence_one_timeline_merge);
+	err += RUN_TEST(test_fence_merge_same_fence);
 
 	if (err)
 		printf("[FAIL]\tsync errors: %d\n", err);