perf ui/helpline: Introduce ui_helpline__vshow()

The ui_helpline__vshow() will be used for pr_* functions.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/1352911664-24620-3-git-send-email-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/ui/helpline.c b/tools/perf/ui/helpline.c
index a49bcf3..700fb3c 100644
--- a/tools/perf/ui/helpline.c
+++ b/tools/perf/ui/helpline.c
@@ -16,9 +16,16 @@
 {
 }
 
+static int nop_helpline__show(const char *fmt __maybe_unused,
+			       va_list ap __maybe_unused)
+{
+	return 0;
+}
+
 static struct ui_helpline default_helpline_fns = {
 	.pop	= nop_helpline__pop,
 	.push	= nop_helpline__push,
+	.show	= nop_helpline__show,
 };
 
 struct ui_helpline *helpline_fns = &default_helpline_fns;
@@ -59,3 +66,8 @@
 	ui_helpline__pop();
 	ui_helpline__push(msg);
 }
+
+int ui_helpline__vshow(const char *fmt, va_list ap)
+{
+	return helpline_fns->show(fmt, ap);
+}