fix memory leak pointed out by cinap

Reference: /n/atom/patch/applied2013/testolder1
Date: Mon Jun  3 04:30:22 CES 2013
Signed-off-by: quanstro@quanstro.net

--- /sys/src/cmd/test.c	Mon Jun  3 04:30:05 2013
+++ /sys/src/cmd/test.c	Mon Jun  3 04:30:06 2013
@@ -373,8 +373,9 @@
 	if(rel)
 		n = time(0) - n;
 	if(n < 0)
-		return 0;
-	r = dir->mtime < n;
+		r =  0;
+	else
+		r = dir->mtime < n;
 
 	free(dir);
 	return r;