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/prime_nv_test.c

@@ -506,7 +506,7 @@ int main(int argc, char **argv)
 #define xtest(name) \
 	igt_subtest(#name) \
 		if (test_##name()) \
-			exit(2);
+			igt_fail(2);
 
 	xtest(i915_nv_sharing);
 	xtest(nv_i915_sharing);