Log Message:
Update xmess to 0.83.1.

Changes since 0.82.1:
* Everything from MAME 0.83 and MESS 0.83 (changes-mess.html).
* The Xv driver now turns on XV_AUTOPAINT_COLORKEY, in case it was
  turned off by, for example, by the xine movie player. This prevents the
  display from being blank in this case. (Shyouzou Sugitani)