add missing prototype jack_messagebuffer_thread_init ()

git-svn-id: svn+ssh://jackaudio.org/trunk/jack@3893 0c269be4-1314-0410-8aa9-9f06e86f4224

jack/messagebuffer.h

@@ -39,4 +39,6 @@ void jack_message_buffer_thread_init (void (*cb)(void*), void*);
 
 void jack_messagebuffer_add(const char *fmt, ...);
 
+void jack_messagebuffer_thread_init (void (*cb)(void*), void* arg);
+
 #endif /* __jack_messagebuffer_h__ */