sk-unix: fix uint32_t id variable printf format specifier

coverity CID 389193:
CID 389193 (#1 of 1): Printf format string issue (PW.BAD_PRINTF_FORMAT_STRING)
1. bad_printf_format_string: invalid format string conversion
598 pr_warn("Can't stat socket %#x(%s), skipping: %m (err %d)\n", id, rpath, errno);

Specifier "%#x" is wrong for id as it is of type uint32_t, let's change
it to "%#" PRIx32 "" to fix the problem.

Signed-off-by: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>

criu/sk-unix.c

@@ -595,7 +595,7 @@ static int unix_resolve_name_old(int lfd, uint32_t id, struct unix_sk_desc *d, U
 	snprintf(rpath, sizeof(rpath), ".%s", name);
 	if (fstatat(mntns_root, rpath, &st, 0)) {
 		if (errno != ENOENT) {
-			pr_warn("Can't stat socket %#x(%s), skipping: %m (err %d)\n", id, rpath, errno);
+			pr_warn("Can't stat socket %#" PRIx32 "(%s), skipping: %m (err %d)\n", id, rpath, errno);
 			goto skip;
 		}