i965: Move BRW_NEW_*_PROG_DATA flags to .brw (not .cache).

i965: Move BRW_NEW_*_PROG_DATA flags to .brw (not .cache).

I put the BRW_NEW_*_PROG_DATA flags at the beginning so that
brw_state_cache.c can still continue using 1 << brw_cache_id.

I also added a comment explaining the difference between
BRW_NEW_*_PROG_DATA and BRW_NEW_*_PROGRAM, as it took me a long time
to remember it.

Non-mechanical changes:
- brw_state_cache.c and brw_ff_gs.c now signal .brw, not .cache.
- brw_state_upload.c - INTEL_DEBUG=state changes.
- brw_context.h - bit definition merging.

v2: Correct the explanation of BRW_NEW_*_PROG_DATA to mention
    state-based recompiles, and nix the "proper subset" claim,
    as it's false. (Caught by Kristian Høgsberg).

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Kristian Høgsberg <krh@bitplanet.net>
Reviewed-by: Matt Turner <mattst88@gmail.com>