tests: roll out igt_simple_init/igt_simple_main

Also use igt_skip a bit more to simplify some of the tests.

Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

tests/gem_unref_active_buffers.c

@@ -51,7 +51,7 @@ static drm_intel_bufmgr *bufmgr;
 struct intel_batchbuffer *batch;
 static drm_intel_bo *load_bo;
 
-int main(int argc, char **argv)
+igt_simple_main
 {
 	int fd, i;
 
@@ -96,6 +96,4 @@ int main(int argc, char **argv)
 	drm_intel_bufmgr_destroy(bufmgr);
 
 	close(fd);
-
-	return 0;
 }