Partially revert commit 1828.  There is no safe way to detect whether a thread has exited with pthreads although this is easy in Windows.
Partially revert commit 1828.  There is no safe way to detect whether a thread has exited with pthreads although this is easy in Windows.

git-svn-id: 98787b36aaefbae4b30fa755be920954cd25e1e4@1830 ae7d391e-3f74-4a2b-a0db-a8776840fd2a

polyml/polyml,dcjm/polyml,mn200/polyml,dcjm/polyml,dcjm/polyml,mn200/polyml,polyml/polyml,dcjm/polyml,mn200/polyml,polyml/polyml,polyml/polyml,mn200/polyml