The function rb_update_write_stamp() is in the hotpath of the ring buffer
recording. Make sure that it is inlined as well. There's not many places
that call it.

Link: http://lkml.kernel.org/r/20161121183700.GW26852@two.firstfloor.orgReported-by: NAndi Kleen <andi@firstfloor.org>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>