Remove intel pageflipping support in its entirety.

It's been broken and deprecated for a while, so it's time to die. This has the
wonderful benefit of cleaning up the code a fair amount; making it marginally
less twisty.

I'm unsure if the for loops in IntelWindowMoved are still needed.

src/mesa/drivers/dri/intel/intel_blit.c

@@ -544,7 +544,6 @@ intelClearWithBlit(GLcontext *ctx, GLbitfield mask)
                   _mesa_debug(ctx, "hardware blit clear buf %d rb id %d\n",
                   buf, irb->Base.Name);
                 */
-	       intel_wait_flips(intel);
 
                assert(b.x1 < b.x2);
                assert(b.y1 < b.y2);