perf hists: Add support for showing relative percentage

perf hists: Add support for showing relative percentage

When filtering by thread, dso or symbol on TUI it also update total
period so that the output shows different result than no filter - the
percentage changed to relative to filtered entries only.  Sometimes
this is not desired since users might expect same results with filter.

So new filtered_* fields to hists->stats to count them separately.
They'll be controlled/used by user later.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/1397145720-8063-2-git-send-email-namhyung@kernel.org
Signed-off-by: Jiri Olsa <jolsa@redhat.com>