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_double_irq_loop.c

@@ -91,7 +91,7 @@ dummy_reloc_loop(void)
 	}
 }
 
-int main(int argc, char **argv)
+igt_simple_main
 {
 	int fd;
 	int devid;
@@ -125,6 +125,4 @@ int main(int argc, char **argv)
 	drm_intel_bufmgr_destroy(bufmgr);
 
 	close(fd);
-
-	return 0;
 }