The recent change to mkclass() was letting genocided monsters be
created when role-specific monsters were chosen for quest levels.
makemon(Null) -> rndmonst() -> qt_montype() -> mkclass() -> mk_gen_ok()
was accepting members of the quest-specified class even when they
should have been rejected. I'm still not sure why the revised bit
manipulation didn't work as intended; the re-revised code does.
G_IGNORE was a bug waiting to happen since it gets passed to
mkclass() as a mons[].geno flag but is used to control the use of
mvitals[].mvflags values. It's still being misused but at least
it doesn't conflict with any of the other flags now.
Fixes#352
8c1120261a