Merge branch 'for-3.20' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu

Pull percpu changes from Tejun Heo:
 "Nothing too interesting.  One cleanup patch and another to add a
  trivial state check function"

* 'for-3.20' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu:
  percpu_ref: implement percpu_ref_is_dying()
  percpu_ref: remove unnecessary ACCESS_ONCE() in percpu_ref_tryget_live()