Ruby

• thread_pthread.c (thread_timer): add to care a spurious wakeup.
  When native_cond_timedwait() return 0 by spurious wakeup, we
  don't have to neither 1) call timer_thread_function and 2)
  exit the timer thread.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@31926 b2dd03c8-39d4-4d8f-98ff-823fe69b080e