files: change error to warning in linkat_hard error path

We print errors in all error cases when calling linkat_hard anyway, but
for some errors like EEXIST we are fine and just skip them, so we should
not print error here.
Signed-off-by: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>

criu/files-reg.c

@@ -1366,7 +1366,7 @@ static int linkat_hard(int odir, char *opath, int ndir, char *npath, uid_t uid,
 
 	if (!( (errno == EPERM || errno == EOVERFLOW) && (root_ns_mask & CLONE_NEWUSER) )) {
 		errno_save = errno;
-		pr_perror("Can't link %s -> %s", opath, npath);
+		pr_warn("Can't link %s -> %s", opath, npath);
 		errno = errno_save;
 		return ret;
 	}