Allow mpi_init_thread to override the MPI_THREAD_LEVEL

Signed-off-by: Austen Lauria <awlauria@us.ibm.com>
(cherry picked from commit babfd93)

Author: AboorvaDevarajan

ompi/mpi/c/init_thread.c

@@ -48,9 +48,14 @@ int MPI_Init_thread(int *argc, char ***argv, int required,
                     int *provided)
 {
     int err;
+    char *env;
 
     ompi_hook_base_mpi_init_thread_top(argc, argv, required, provided);
 
+    if (NULL != (env = getenv("OMPI_MPI_THREAD_LEVEL")))  {
+        required = atoi(env);
+    }
+ 
     if ( MPI_PARAM_CHECK ) {
         if (required < MPI_THREAD_SINGLE || required > MPI_THREAD_MULTIPLE) {
             ompi_mpi_errors_are_fatal_comm_handler(NULL, NULL, FUNC_NAME);