restore: Save some time mounting proc

When restoring w/o namespaces it doesn't make sence to
mount /proc by hands and detach it. We can just use the
host-side one.
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>

criu/cr-restore.c

@@ -1249,6 +1249,9 @@ static int mount_proc(void)
 	int fd, ret;
 	char proc_mountpoint[] = "crtools-proc.XXXXXX";
 
+	if (root_ns_mask == 0)
+		fd = ret = open("/proc", O_DIRECTORY);
+	else {
 		if (mkdtemp(proc_mountpoint) == NULL) {
 			pr_perror("mkdtemp failed %s", proc_mountpoint);
 			return -1;
@@ -1262,6 +1265,8 @@ static int mount_proc(void)
 		}
 
 		ret = fd = open_detach_mount(proc_mountpoint);
+	}
+
 	if (fd >= 0) {
 		ret = set_proc_fd(fd);
 		close(fd);