i965: Don't flush the batch immediately on EndQuery.

i965: Don't flush the batch immediately on EndQuery.

The theory I had when I wrote the code was that you wanted to minimize latency
on your queries because the app was going to ask soon.  Only, it turns out
that everybody batches up their queries and asks for the results later (often
after the next SwapBuffers!), so this was a pessimization.

Until now, I had no workload where it mattered enough to benchmark.  Recently
I started playing some Minecraft, which uses tons of queries to decide whether
to render chunks of the terrain.  For that app, avoiding the flush in the
query-generation loop improves performance 22.7% +/- 4.7% (n=3) on an apitrace
capture of it (confirmed in game by watching the fps meter found by pressing
F3, 15/16 -> 20/21 fps).

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>