files: Do not lost original errno value

The callers of rfi_remap() are interested in a errno,
linkat_hard() returns. So, preserve errno before we
call rm_parent_dirs().
Reported-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Acked-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>

criu/files-reg.c

@@ -1418,7 +1418,9 @@ out_root:
 
 	if (linkat_hard(mntns_root, rpath, mntns_root, path,
 			rfi->remap->uid, rfi->remap->gid, 0) < 0) {
+		int errno_saved = errno;
 		rm_parent_dirs(mntns_root, path, *level);
+		errno = errno_saved;
 		return -1;
 	}