i965: Move program cache printing to brw_program_cache.c.

i965: Move program cache printing to brw_program_cache.c.

It makes sense to put a function which prints out the entire contents
of the program cache in the file that implements the program cache.

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Eduardo Lima Mitev <elima@igalia.com>