9fs: use srv to retry dial when necessary
 [rsc] --rwxrwxr-x M 628694 glenda sys 927 Apr 10 12:08 rc/bin/9fs
	/n/sourcesdump/2006/0410/plan9/rc/bin/9fs:20,42 - 
	/n/sourcesdump/2006/0411/plan9/rc/bin/9fs:20,39
	  case juke
	  	srv -q il!jukefs && mount /srv/il!jukefs /n/njuke && bind -c /n/njuke/juke /n/juke
	  case sources
	- 	srv -q tcp!sources.cs.bell-labs.com sources
	- 	mount -n /srv/sources /n/sources
	+ 	srv -nq tcp!sources.cs.bell-labs.com sources /n/sources
	  case sourcesdump
	  	9fs sources
	- 	mount /srv/sources /n/sourcesdump main/archive
	+ 	mount -n /srv/sources /n/sourcesdump main/archive
	  case sourcessnap
	  	9fs sources
	- 	mount /srv/sources /n/sourcessnap main/snapshot
	+ 	mount -n /srv/sources /n/sourcessnap main/snapshot
	  case wiki
	- 	srv 'net!plan9.bell-labs.com!wiki' wiki	
	- 	mount /srv/wiki /mnt/wiki
	+ 	srv -m 'net!plan9.bell-labs.com!wiki' wiki /mnt/wiki
	  case *
	  	switch($#*){
	  	case 1
	  		srv -m $1
	  	case *
	- 		srv $1
	- 		mount -c /srv/$1 $2
	+ 		srv -m $1 $1 $2
	  	}
	  }