Log Message:
Update xmame to version 0.78.1.

Changes since 0.77.1 includes:
- Everything from MAME 0.78
- Changed the abbreviation of "-pause_brightness" to "-pbrt" \ 
to prevent
  a conflict with "-playback".
- Fixed an infrequent spurious error reported by zlib 1.2.1.  (Mark
  Adler)