perf hists: Factor output_resort from hists__output_resort

perf hists: Factor output_resort from hists__output_resort

Currently hists__output_resort() depends on hists based on hists_evsel
struct, but we need to be able to sort common hists as well.

Cutting out the sorting base sorting code into output_resort
function, so it can be reused in following patch.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1453109064-1026-2-git-send-email-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>