i965: When dumping programs, dump the whole cache. But don't by default.

i965: When dumping programs, dump the whole cache.  But don't by default.

The previous brw_state_dump output was rather useless -- last used
program per batch, and just the hex.  Now we dump all programs (since
we don't know which were used), and disassemble them.  But that's a
ton of spam, and usually when looking into program contents we use
INTEL_DEBUG={vs,wm,misc,other} and when looking into state updates we
use INTEL_DEBUG=batch, so this dump usually just massively clutters up
the output.

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