perf gtk/hists: Set rules hint for the hist browser

The 'rules' means that every second line of the tree view has a shaded
background, which makes it easier to see which cell belongs to which
row in the tree view.  It can be useful for a tree view that has a lot
of rows.
Reviewed-by: NPekka Enberg <penberg@kernel.org>
Signed-off-by: NNamhyung Kim <namhyung@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1370337737-30812-7-git-send-email-namhyung@kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/ui/gtk/hists.c

@@ -326,6 +326,8 @@ static void perf_gtk__show_hists(GtkWidget *window, struct hists *hists,
 		}
 	}
 
+	gtk_tree_view_set_rules_hint(GTK_TREE_VIEW(view), TRUE);
+
 	g_signal_connect(view, "row-activated",
 			 G_CALLBACK(on_row_activated), NULL);
 	gtk_container_add(GTK_CONTAINER(window), view);