tracing: Remove unused declaration of trace_stop_cmdline_recording

trace_stop_cmdline_recording declaration isn't in use, remove it.

Link: http://lkml.kernel.org/r/20170609025327.9508-2-joelaf@google.com

Cc: kernel-team@android.com
Cc: Ingo Molnar <mingo@redhat.com>
Signed-off-by: Joel Fernandes <joelaf@google.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

kernel/trace/trace.c

@@ -1910,8 +1910,6 @@ static void tracing_stop_tr(struct trace_array *tr)
 	raw_spin_unlock_irqrestore(&tr->start_lock, flags);
 }
 
-void trace_stop_cmdline_recording(void);
-
 static int trace_save_cmdline(struct task_struct *tsk)
 {
 	unsigned pid, idx;