tools lib traceevent: Add pevent_unregister_print_function()

When a plugin unloaded it needs to unregister its print handler from
pevent.

So add an unregister function to do it.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Reviewed-by: Jiri Olsa <jolsa@redhat.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung.kim@lge.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/1389839478-5887-3-git-send-email-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/lib/traceevent/event-parse.h b/tools/lib/traceevent/event-parse.h
index c48acfb..791c539 100644
--- a/tools/lib/traceevent/event-parse.h
+++ b/tools/lib/traceevent/event-parse.h
@@ -631,6 +631,8 @@
 				   pevent_func_handler func,
 				   enum pevent_func_arg_type ret_type,
 				   char *name, ...);
+int pevent_unregister_print_function(struct pevent *pevent,
+				     pevent_func_handler func, char *name);
 
 struct format_field *pevent_find_common_field(struct event_format *event, const char *name);
 struct format_field *pevent_find_field(struct event_format *event, const char *name);