perf callchain: Add enum match_result for match_chain()

perf callchain: Add enum match_result for match_chain()

The append_chain() might return either result of match_chain() or other
(error) code.  But match_chain() can return any value in s64 type so
it's hard to check the error case.  Add new enum match_result and make
match_chain() return non-negative values only so that we can check the
error cases.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/1455631723-17345-5-git-send-email-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>