mesa: stop passing state bitfield to UpdateState()

mesa: stop passing state bitfield to UpdateState()

The code comment which seems to have been added in cab974cf6c2db
(from year 2000) says:

   "Set ctx->NewState to zero to avoid recursion if
   Driver.UpdateState() has to call FLUSH_VERTICES().  (fixed?)"

As far as I can tell nothing in any of the UpdateState() calls
should cause it to be called recursively.

V2: add a wrapper around the osmesa update function so it can still
    be used internally.

Reviewed-by: Brian Paul <brianp@vmware.com>
Reviewed-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>