typo in fs/tarfs's ustar support,
test against /n/sources/9grid/xcpu.tar

Reference: /n/sources/patch/applied/tarfs-ustar
Date: Tue Oct 18 17:09:28 CES 2005

--- /sys/src/cmd/tapefs/tarfs.c	Tue Oct 18 17:07:55 2005
+++ /sys/src/cmd/tapefs/tarfs.c	Tue Oct 18 17:07:52 2005
@@ -61,11 +61,11 @@
 		||  strrchr(dblock.dbuf.name, '\0')[-1] == '/')
 			f.mode |= DMDIR;
 		f.mode &= DMDIR|0777;
-		linkflg = dblock.dbuf.linkflag=='s' || dblock.dbuf.linkflag=='1';
+		linkflg = dblock.dbuf.linkflag=='5' || dblock.dbuf.linkflag=='1';
 		isabs = dblock.dbuf.name[0]=='/';
 		if (chksum != checksum()){
 			fprint(1, "bad checksum on %.28s\n", dblock.dbuf.name);
-			abort();
+			exits("checksum");
 		}
 		if (linkflg) {
 			/*fprint(2, "link %s->%s skipped\n", dblock.dbuf.name,