tests: use igt_fail instead of exit(param != 0)

Mostly a sed job with too manual fixups:
- one case of using _exit instead of exit
- and one case which under some conditions use 77, so convert that
  check to an igt_skip.

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

tests/gem_hang.c

@@ -74,7 +74,7 @@ int main(int argc, char **argv)
 	if (argc != 2) {
 		fprintf(stderr, "usage: %s <disabled pipe number>\n",
 			argv[0]);
-		exit(-1);
+		igt_fail(-1);
 	}
 
 	bad_pipe = atoi(argv[1]);