mpit: define correct names for source ordering

The enum for MPI_T_source_order was not correct.
Found while working on the ABI effort open-mpi#13280

Signed-off-by: Howard Pritchard <howardp@lanl.gov>

Author: hppritcha

ompi/include/mpi.h.in

@@ -954,8 +954,8 @@ typedef enum {
  * MPIT source ordering
  */
 enum ompi_mpi_t_source_order_t {
-  MPI_T_ORDERED,
-  MPI_T_UNORDERED,
+  MPI_T_SOURCE_ORDERED,
+  MPI_T_SOURCE_UNORDERED,
 };
 
 typedef enum ompi_mpi_t_source_order_t MPI_T_source_order;