tracing: remove unused ftrace_output_event() prototype

The prototype of ftrace_output_event was added by commit 1d6bae966e90
("tracing: Move raw output code from macro to standalone function")
but this function was not defined anywhere, and is still nowhere to be
found.

Link: http://lkml.kernel.org/r/1430648282-25792-1-git-send-email-nicolas.iooss_linux@m4x.org

Signed-off-by: Nicolas Iooss <nicolas.iooss_linux@m4x.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

include/linux/ftrace_event.h

@@ -219,9 +219,6 @@ struct ftrace_event_class {
 extern int ftrace_event_reg(struct ftrace_event_call *event,
 			    enum trace_reg type, void *data);
 
-int ftrace_output_event(struct trace_iterator *iter, struct ftrace_event_call *event,
-			char *fmt, ...);
-
 int ftrace_event_define_field(struct ftrace_event_call *call,
 			      char *type, int len, char *item, int offset,
 			      int field_size, int sign, int filter);