Fix the POSIX timers fix.

If we're not going to wait for the timer threads to exit, we need
another way to ensure that we don't free the data they're using
prematurely. The easiest way to ensure that is to let them free the
data themselves.

Change-Id: Icee17c87bbcb9c3aac5868973f595d08569f33aa
Merge "Fix the POSIX timers fix."
auto-merger: merge in from aosp/master