Adding FTRACE_ENTRY_REG macro so particular ftrace entries
could specify registration function and thus become accesible
via perf.

This will be used in upcomming patch for function trace.

Link: http://lkml.kernel.org/r/1329317514-8131-5-git-send-email-jolsa@redhat.comAcked-by: NFrederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: NJiri Olsa <jolsa@redhat.com>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>