perf ui: Introduce struct ui_helpline

Add struct ui_helpline in order to provide flexible implementation of
helpline APIs.  And convert existing TUI implementation to use it.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1345104894-14205-1-git-send-email-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/ui/helpline.h b/tools/perf/ui/helpline.h
index 7bab6b3..61118b2 100644
--- a/tools/perf/ui/helpline.h
+++ b/tools/perf/ui/helpline.h
@@ -4,13 +4,21 @@
 #include <stdio.h>
 #include <stdarg.h>
 
+struct ui_helpline {
+	void (*pop)(void);
+	void (*push)(const char *msg);
+};
+
+extern struct ui_helpline *helpline_fns;
+
 void ui_helpline__init(void);
+
 void ui_helpline__pop(void);
 void ui_helpline__push(const char *msg);
 void ui_helpline__vpush(const char *fmt, va_list ap);
 void ui_helpline__fpush(const char *fmt, ...);
 void ui_helpline__puts(const char *msg);
 
-extern char ui_helpline__current[];
+extern char ui_helpline__current[512];
 
 #endif /* _PERF_UI_HELPLINE_H_ */