mesa: do FLUSH_VERTICES() in _mesa_flush/finish()
mesa: do FLUSH_VERTICES() in _mesa_flush/finish()

This was being done in the _mesa_Flush/Finish() calls but if there
was an internal call to _mesa_flush/finish() the FLUSH_VERTICES()
wouldn't happen.  Looks like only the intel and radeon drivers made
such calls in MakeCurrent().

benaadams/glsl-optimizer,benaadams/glsl-optimizer,djreep81/glsl-optimizer,djreep81/glsl-optimizer,mcanthony/glsl-optimizer,mcanthony/glsl-optimizer,dellis1972/glsl-optimizer,wolf96/glsl-optimizer,zeux/glsl-optimizer,mapbox/glsl-optimizer,dellis1972/glsl-optimizer,zz85/glsl-optimizer,mapbox/glsl-optimizer,zz85/glsl-optimizer,tokyovigilante/glsl-optimizer,dellis1972/glsl-optimizer,wolf96/glsl-optimizer,jbarczak/glsl-optimizer,mapbox/glsl-optimizer,dellis1972/glsl-optimizer,benaadams/glsl-optimizer,zeux/glsl-optimizer,dellis1972/glsl-optimizer,tokyovigilante/glsl-optimizer,mapbox/glsl-optimizer,tokyovigilante/glsl-optimizer,tokyovigilante/glsl-optimizer,jbarczak/glsl-optimizer,mcanthony/glsl-optimizer,benaadams/glsl-optimizer,wolf96/glsl-optimizer,bkaradzic/glsl-optimizer,mcanthony/glsl-optimizer,zz85/glsl-optimizer,zeux/glsl-optimizer,zeux/glsl-optimizer,jbarczak/glsl-optimizer,benaadams/glsl-optimizer,bkaradzic/glsl-optimizer,mapbox/glsl-optimizer,jbarczak/glsl-optimizer,djreep81/glsl-optimizer,djreep81/glsl-optimizer,zz85/glsl-optimizer,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,bkaradzic/glsl-optimizer,zz85/glsl-optimizer,djreep81/glsl-optimizer,benaadams/glsl-optimizer,mcanthony/glsl-optimizer,metora/MesaGLSLCompiler,bkaradzic/glsl-optimizer,wolf96/glsl-optimizer,zeux/glsl-optimizer,wolf96/glsl-optimizer,tokyovigilante/glsl-optimizer,jbarczak/glsl-optimizer,zz85/glsl-optimizer,bkaradzic/glsl-optimizer