perf unwind: Add initialized arg into unwind__prepare_access

Adding initialized arg into unwind__prepare_access to get feedback about
the initialization state.

It's not possible to get it from error code, because we return 0 even in
case we don't recognize dso, which is valid.

The 'initialized' value is used in following patch to speedup
unwind__prepare_access calls logic in fork path.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: He Kuang <hekuang@huawei.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1467634583-29147-4-git-send-email-jolsa@kernel.org


[ Remove ; after static inline function signatures, fixes build break ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>