Update games/moon-buggy to moon-buggy-1.0.51, based on patches from
Benedek Gergely via pkgsrc-users@.
ok wiz@

pkgsrc changes:
* Convert the package to USE_GAMESGROUP and adjust permission in order to have a
  global scorefile for all users (previously moon-buggy used as its scorefile
  in ~/.mbscore)

Changes:
* Increase the version string to "1.0.51".
* Minor MacOSX compatibility fix.
* highscore.c, realname.c: fix highscore file corruption bug
  (thanks, Arnd Behring)
* update the NEWS file
* update the copyright dates

(leot)