perf ui/tui: Fix off-by-one in hist_browser__update_nr_entries()

The nr_entries variable is increased inside the loop in the function
but it always count the first entry regardless of it's filtered or
not; caused an off-by-one error.

It'd become a problem especially there's no entry at all - it'd get a
segfault during referencing a NULL pointer.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/1398327843-31845-9-git-send-email-namhyung@kernel.org
Signed-off-by: Jiri Olsa <jolsa@kernel.org>

tools/perf/ui/browsers/hists.c

@@ -1348,10 +1348,10 @@ static void hist_browser__update_pcnt_entries(struct hist_browser *hb)
 	u64 nr_entries = 0;
 	struct rb_node *nd = rb_first(&hb->hists->entries);
 
-	while (nd) {
+	while ((nd = hists__filter_entries(nd, hb->hists,
+					   hb->min_pcnt)) != NULL) {
 		nr_entries++;
-		nd = hists__filter_entries(rb_next(nd), hb->hists,
-					   hb->min_pcnt);
+		nd = rb_next(nd);
 	}
 
 	hb->nr_pcnt_entries = nr_entries;