tests: let output damage skip without color ops

If the compositor does not have the shadow buffer capability (implied by
the color ops capability bit), then trying to run the shadow buffer test
is useless, it would just fail. Let it skip instead.

Fixes: b1e56143c5

Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.com>

tests/output-damage-test.c

@@ -141,6 +141,10 @@ fixture_setup(struct weston_test_harness *harness, const struct setup_args *arg)
 		 * that step.
 		 */
 		setup.test_quirks.gl_force_full_redraw_of_shadow_fb = true;
+
+		/* To skip instead of fail the test if shadow not available */
+		setup.test_quirks.required_capabilities = WESTON_CAP_COLOR_OPS;
+
 		weston_ini_setup(&setup,
 				 cfgln("[output]"),
 				 cfgln("name=headless"),