Those function pointers will be used to sort report output based on
the selected fields.  This is a preparation of later change.
Signed-off-by: NNamhyung Kim <namhyung@kernel.org>
Acked-by: NIngo Molnar <mingo@kernel.org>
Link: http://lkml.kernel.org/r/1400480762-22852-2-git-send-email-namhyung@kernel.orgSigned-off-by: NJiri Olsa <jolsa@kernel.org>