perf report: Merge al->filtered with hist_entry->filtered

I.e. don't drop al->filtered entries, create the hist_entries and use
its ->filtered bitmap, that is kept with the same semantics for its
bitmap, leaving the filtering to be done at the hist_entry level, i.e.
in the UIs.

This will allow zooming in/out the filters.

Signed-off-by: Namhyung Kim <namhyung.kim@lge.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung.kim@lge.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/n/tip-xeyhkepu7plw716lrtb0zlnu@git.kernel.org
[ yanked this out of a previous patch ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>