tracing: Set user_events to BROKEN

After being merged, user_events become more visible to a wider audience
that have concerns with the current API. It is too late to fix this for
this release, but instead of a full revert, just mark it as BROKEN (which
prevents it from being selected in make config). Then we can work finding
a better API. If that fails, then it will need to be completely reverted.

Link: https://lore.kernel.org/all/2059213643.196683.1648499088753.JavaMail.zimbra@efficios.com/
Link: https://lkml.kernel.org/r/20220330155835.5e1f6669@gandalf.local.homeSigned-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

kernel/trace/Kconfig

@@ -741,6 +741,7 @@ config USER_EVENTS
 	bool "User trace events"
 	select TRACING
 	select DYNAMIC_EVENTS
+	depends on BROKEN || COMPILE_TEST # API needs to be straighten out
 	help
 	  User trace events are user-defined trace events that
 	  can be used like an existing kernel trace event.  User trace