i965: Add a type argument to brw_state_batch().

i965: Add a type argument to brw_state_batch().

I want to make brw_state_dump.c handle more than just the last
statechange, so I want to keep track of what's in the batch state.  By
using AUB file numbering for most of these packets, this may be
reusable for aub dumping.

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