perf browsers: Add live mode to the hists, annotate browsers

This allows passing a timer to be run periodically, which will update
the hists tree that then gers refreshed on the screen, just like the
Live mode (symbol entries, annotation) we already have in 'perf top
--tui'.

Will be used by the new hist_entry/hists based 'top' tool.

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-2r44qd8oe4sagzcgoikl8qzc@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/evlist.c

@@ -533,3 +533,9 @@ bool perf_evlist__sample_id_all(const struct perf_evlist *evlist)
 	first = list_entry(evlist->entries.next, struct perf_evsel, node);
 	return first->attr.sample_id_all;
 }
+
+void perf_evlist__set_selected(struct perf_evlist *evlist,
+			       struct perf_evsel *evsel)
+{
+	evlist->selected = evsel;
+}