don't quit while creating X11 listening socket.
http://mail-index.netbsd.org/current-users/2002/09/16/0005.html
got from portable. markus ok
+ - djm@cvs.openbsd.org 2002/09/19 01:58:18
+ [ssh.c sshconnect.c]
+ bugzilla.mindrot.org #223 - ProxyCommands don't exit.
+ Patch from dtucker@zip.com.au; ok markus@
20020912
- (djm) Made GNOME askpass programs return non-zero if cancel button is