Fold monop.ext (which was extern data decls) into monop.h and deck.h.
Fold monop.def (which had definitions for the extern data) into monop.c.
Fold brd.dat/mon.dat/prop.dat (which were array initializers for some of
the data) into monop.c.
Rearrange includes accordingly. No functional change.
- If a player goes bankrupt buying a property (which shouldn't be
allowed, but I guess it is), don't cause them to resign to themselves.
- Use "NULL", not "0", for pointers.
- Avoid undefined behavior adjusting the current player after resigning.
- Don't leak the memory used to store player names.
The last of these is disabled for the moment because we have the pointers
in question tagged const. Will see to this when I'm finished merging.
This merges in all such remaining changes from the Linux port of the
NetBSD games, except in hunt (where substantial changes from OpenBSD
need to be looked at).
Some such changes were previously covered in PRs bin/6041, bin/6146,
bin/6148, bin/6150, bin/6151, bin/6580, bin/6660, bin/7993, bin/7994,
bin/8039, bin/8057 and bin/8093.
