perf build-id: Move disable_buildid_cache() to util/build-id.c

Also move static variable no_buildid_cache and check it in the
perf_session_cache_build_ids().

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Aravinda Prasad <aravinda@linux.vnet.ibm.com>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: Hemant Kumar <hemant@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Pekka Enberg <penberg@iki.fi>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Vasant Hegde <hegdevasant@linux.vnet.ibm.com>
Cc: systemtap@sourceware.org
Link: http://lkml.kernel.org/r/1415368677-3794-1-git-send-email-namhyung@kernel.org


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>