perf annotate: Fix 'annotate.use_offset' config variable usage

The annotate__configs should be sorted so that it can use bsearch(3).

However commit 0c4a5bce

 ("perf annotate: Display total number of
samples with --show-total-period") added a new config item at the end.
This resulted in the 'annotate.use_offset' config variable cannot be
found and perf terminated like below:

  $ perf report
  bad config file line 6 in ~/.perfconfig

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Martin Liška <mliska@suse.cz>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Taeung Song <treeze.taeung@gmail.com>
Fixes: 0c4a5bce

 ("perf annotate: Display total number of samples with --show-total-period")
Link: http://lkml.kernel.org/r/1445396240-3428-1-git-send-email-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>