remove ..; from sources

Reference: /n/atom/patch/applied2013/tarfsnodotdot
Date: Thu Oct  3 20:47:38 CES 2013
Signed-off-by: quanstro@quanstro.net

--- /sys/src/cmd/tapefs/tarfs.c	Thu Oct  3 20:47:23 2013
+++ /sys/src/cmd/tapefs/tarfs.c	Thu Oct  3 20:47:24 2013
@@ -144,10 +144,12 @@
 		}
 		f.mode &= DMDIR | 0777;
 
-		/* make file name safe and canonical */
+		/* make file name safe, canonical and free of . and .. */
 		while (fname[0] == '/')		/* don't allow absolute paths */
 			++fname;
 		cleanname(fname);
+		while (strncmp(fname, "../", 3) == 0)
+			fname += 3;
 
 		/* reject links */
 		linkflg = hp->linkflag == LF_SYMLINK1 ||