perf hists: Fix recalculation of total_period when sorting entries

perf hists: Fix recalculation of total_period when sorting entries

We were doing parts of it in hists__collapse_resort and parts of it in
hists__output_resort, leading to a bogus total_period.

Fix it by doing just the filtering operation when collapsing because
there we know that the Zoom operations adds filters just  what is in
hists->entries, not to the new batch of entries being collapsed.

And move all the nr_entries + total_period recalculation to
hists__output_resort since we will traverse all entries anyway there.

Problem introduced when developing threaded addition of new batches
of hist_entries, i.e. post v3.1.

Reported-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-8xyh165h7hmwy0696hu25en6@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>