The vmng buffer methods seem to handle both Buffer and GrBUffer.
But in the m4Preflight, a GrBuffer is cast to a BUffer to pass
to a method that turns around and casts it back to a void * to
pass it to vmng_screen_find. As such, I've made several methods
simply take in a void * directly that can be either
The M4 engine has it's own globals array and constants,
so it was cleaner to have it remain as Globals, and change
the ScummVM Globals class to Vars to disambiguate it
Paul Gilbert