wizard mode ^V crash in endgame

wizard mode ^V crash in endgame

     Mentioned in passing in the newsgroup:  level teleporting in the
endgame--which is only possible in wizard mode--can crash if you're
confused.  The change to make confusion sometimes override teleport
control means that sometimes a random destination will be chosen, and
the routine to choose a random level can call rn2() with a value less
than 1 in the endgame, possibly resulting in attempt to divide by 0.

     There's something fishy about the min_/max_depth stuff for the
endgame, but I haven't attempted to figure that out.  This just makes
the random destination always be the current level when in the endgame
so that the problem can't come up.