Call traceoff trigger after the event is recorded.
Since current traceoff trigger is called before recording
the event, we can not know what event stopped tracing.

Typical usecase of traceoff/traceon trigger is tracing
function calls and trace events between a pair of events.
For example, trace function calls between syscall entry/exit.
In that case, it is useful if we can see the return code
of the target syscall.

Link: http://lkml.kernel.org/r/147335074530.12462.4526186083406015005.stgit@devboxSigned-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>