tests/uid.c: use libtests

* tests/uid.c: Use SKIP_MAIN_UNDEFINED.
(main): Use perror_msg_and_skip.
diff --git a/tests/uid.c b/tests/uid.c
index 28e42ed..5da0471 100644
--- a/tests/uid.c
+++ b/tests/uid.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2014-2015 Dmitry V. Levin <ldv@altlinux.org>
+ * Copyright (c) 2014-2016 Dmitry V. Levin <ldv@altlinux.org>
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -26,15 +26,8 @@
  */
 
 #include "tests.h"
-#include <assert.h>
-#include <stdlib.h>
-#include <unistd.h>
-#include <fcntl.h>
 #include <sys/syscall.h>
 
-int
-main(void)
-{
 #if (defined __NR_getuid || defined __NR_getxuid) \
  && defined(__NR_setuid) \
  && defined(__NR_getresuid) \
@@ -42,13 +35,22 @@
  && defined(__NR_setresuid) \
  && defined(__NR_fchown) \
  && defined(__NR_getgroups)
+
+# include <assert.h>
+# include <stdlib.h>
+# include <unistd.h>
+# include <fcntl.h>
+
+int
+main(void)
+{
 	int uid;
 	int size;
 	int *list = 0;
 
-#ifndef __NR_getuid
-# define __NR_getuid __NR_getxuid
-#endif
+# ifndef __NR_getuid
+#  define __NR_getuid __NR_getxuid
+# endif
 	uid = syscall(__NR_getuid);
 
 	(void) close(0);
@@ -60,7 +62,7 @@
 			buf[n] = '\0';
 			n = atoi(buf);
 			if (uid == n)
-				return 77;
+				error_msg_and_skip("getuid() == overflowuid");
 		}
 		(void) close(0);
 	}
@@ -81,7 +83,12 @@
 	assert(list = calloc(size + 1, sizeof(*list)));
 	assert(syscall(__NR_getgroups, size, list) == size);
 	return 0;
-#else
-	return 77;
-#endif
 }
+
+#else
+
+SKIP_MAIN_UNDEFINED("(__NR_getuid || __NR_getxuid)"
+		    " && __NR_setuid && __NR_getresuid && __NR_setreuid"
+		    " && __NR_setresuid && __NR_fchown && __NR_getgroups")
+
+#endif