Merge in the modified thread configure option branch per today's telecon.

Remove the --enable-progress-threads option as this is no longer functional, and hardcode OPAL_ENABLE_PROGRESS_THREADS to 0.

Replace the --enable-mpi-threads option with --enable-mpi-thread-multiple as this is clearer as to meaning. This option automatically turns "on" opal thread support if it wasn't already so specified. If the user specifies --disable-opal-multi-threads --enable-mpi-thread-multiple, we will error out with a message

Add a new --enable-opal-multi-threads option that turns "on" opal thread support without doing anything wrt mpi-thread-multiple

This commit was SVN r22841.

ompi/mpi/c/init_thread.c

@@ -52,7 +52,7 @@ int MPI_Init_thread(int *argc, char ***argv, int required,
      *   = MPI_THREAD_MULTIPLE. Such an implementation may always return provided
      *   = MPI_THREAD_MULTIPLE, irrespective of the value of required.
      */
-#if OPAL_ENABLE_MPI_THREADS
+#if OMPI_ENABLE_THREAD_MULTIPLE
     *provided = MPI_THREAD_MULTIPLE;
 #else
     *provided = MPI_THREAD_SINGLE;