perf hists browser: Only 'Zoom into thread' only when sort order has 'pid'

We can't offer a zoom into thread when a bucket (struct hist_entry) may
have samples for more than one thread, i.e. when 'pid' is not part of
the sort order, fix it.
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>,
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/1452960197-5323-9-git-send-email-namhyung@kernel.org
[ Carved out from a  larger patch ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/ui/browsers/hists.c

@@ -1782,7 +1782,7 @@ static int
 add_thread_opt(struct hist_browser *browser, struct popup_action *act,
 	       char **optstr, struct thread *thread)
 {
-	if (thread == NULL)
+	if (!sort__has_thread || thread == NULL)
 		return 0;
 
 	if (asprintf(optstr, "Zoom %s %s(%d) thread",
@@ -2307,10 +2307,12 @@ static int perf_evsel__hists_browse(struct perf_evsel *evsel, int nr_events,
 					     socked_id);
 		/* perf script support */
 		if (browser->he_selection) {
+			if (sort__has_thread && thread) {
 				nr_options += add_script_opt(browser,
 							     &actions[nr_options],
 							     &options[nr_options],
 							     thread, NULL);
+			}
 			/*
 			 * Note that browser->selection != NULL
 			 * when browser->he_selection is not NULL,