I can't take credit for this and still have no idea why it is
needed, but it fixes use of ^V as a command and as input to
to the regular version of yn_function(). In particular, '&'
command reports it as ^V. Unfortunately when 'popup_dialog' is
set, no control characters seem to be accepted by the part of
NetHackQtYnDialog(Exec+KeyPressEvent) responsible for arbitrary
input.
It also causes getlin() to terminate but I can't think of any
situation where ^V would be considered to be valid input for
getlin() so won't worry about that.
I put it in as '#if MACOSX' because I don't know whether any
other Qt platforms need it.
2f76d0e701