i965: Dump more information about batch buffer usage.

i965: Dump more information about batch buffer usage.

Previously, INTEL_DEBUG=bat would dump messages like:

intel_mipmap_tree.c:1643: Batchbuffer flush with 456b used

This only reported the space used for command packets, and didn't
report any information on the space used for indirect state.

Now it dumps:

intel_context.c:366: Batchbuffer flush with 6128b (pkt) + 4288b (state)
= 10416b (31.8%)

This conveniently shows the breakdown of space used for packets vs.
state, as well as the percentage of batchbuffer space.

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Paul Berry <stereotype441@gmail.com>