The Windows config option to point at an X authority file is only

The Windows config option to point at an X authority file is only
read at connection setup time, so don't offer it in the Change
Settings dialog box.

(In particular, this fixes an assertion failure when selecting
Change Settings on a non-SSH connection, since wincfg.c would have
added that control to Connection/SSH/X11 when the parent panel
Connection/SSH didn't exist. Making the control conditional on the
selected protocol would have been sufficient to fix that failure,
but I now realise that the setting should never have been presented
in mid-session in any case.)

[originally from svn r8443]