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 <[email protected]>
Acked-by: Jiri Olsa <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: David Ahern <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Stephane Eranian <[email protected]>
Cc: Wang Nan <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>