Revert part of r20537: per lengtyh discussion on the phone and the

devel list, it ''is'' within in the spirit of MPI to allow
MPI_REQUEST_NULL to be passed to MPI_REQUEST_GET_STATUS.  I filed a
ticket proposal with MPI-2.2 to make this officially accepted:

  https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/137

Plus, r20537 didn't revert out all of the machinery for allowing
MPI_REQUEST_NULL or inactive requests, anyway.  So this commit simply
removes the parameter check that was added in r20537, and we're back
to where we were before this whole conversation.  :-)

This commit was SVN r20616.

The following SVN revision numbers were found above:
  r20537 --> open-mpi/ompi@38aab37bb3

ompi/mpi/c/request_get_status.c

@@ -51,7 +51,7 @@ int MPI_Request_get_status(MPI_Request request, int *flag,
         OMPI_ERR_INIT_FINALIZE(FUNC_NAME);
         if( (NULL == flag) || (NULL == status) ) {
             return OMPI_ERRHANDLER_INVOKE(MPI_COMM_WORLD, MPI_ERR_ARG, FUNC_NAME);
-        } else if (NULL == request || MPI_REQUEST_NULL == request) {
+        } else if (NULL == request) {
             return OMPI_ERRHANDLER_INVOKE(MPI_COMM_WORLD, MPI_ERR_REQUEST,
                                           FUNC_NAME);
         }