manager thread to start only if the timer manager thread is a local
thread, otherwise in native-threads-only mode, if NSPR is initialized
by a DLL, the primordial thread may be hung in PR_WaitCondVar because
the (native) timer manager thread does not get to run until the DLL is
initialized.
git-svn-id: svn://10.0.0.236/trunk@77893 18797224-902f-48f8-a5cc-f745e15eee43