Revert "i965: Move brw_emit_query_begin() to the render ring prelude."

Revert "i965: Move brw_emit_query_begin() to the render ring prelude."

This reverts commit a4bf7f6b6e612626c4e4fc21507ac213a7ba4b00.
It breaks occlusion queries on Gen4-5.  Doing this right will likely
require larger changes, which should be done at a future date.

Some Piglit tests still passed due to other bugs; fixing those revealed
this problem.

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Eric Anholt <eric@anholt.net>