Handle DMDIR bit correctly.
 [rsc] --rw-rw-r-- M 191333 glenda sys 6284 Sep 22 09:04 sys/src/cmd/aux/9pcon.c
	/n/sourcesdump/2005/0922/plan9/sys/src/cmd/aux/9pcon.c:127,133 - 
	/n/sourcesdump/2005/0923/plan9/sys/src/cmd/aux/9pcon.c:127,133
	  {
	  	f->fid = atoi(argv[0]);
	  	f->name = argv[1];
	- 	f->perm = strtol(argv[2], 0, 8);
	+ 	f->perm = strtoul(argv[2], 0, 8);
	  	f->mode = atoi(argv[3]);
	  	return nil;
	  }
 [sys] --rwxrwxr-x M 191333 glenda sys 94916 Sep 22 23:10 386/bin/aux/9pcon
	/sys/src/cmd/aux/9pcon.c:tcreate