As a result of r21308, if we are building with "--disable-mpi-io " make sure that MPI_MAX_DATAREP_STRING is defined in mpi.h

MTT caught builds failing with the following error which flagged the problem:
{{{
param.cc:802: error: ‘MPI_MAX_DATAREP_STRING’ was not declared in this scope
}}}

This commit was SVN r21337.

The following SVN revision numbers were found above:
  r21308 --> open-mpi/ompi@2f9765926e

ompi/include/mpi.h.in

@@ -431,9 +431,10 @@ typedef int (MPI_Grequest_cancel_function)(void *, int);
 #define MPI_SEEK_CUR               602
 #define MPI_SEEK_END               604
 
-#define MPI_MAX_DATAREP_STRING OPAL_MAX_DATAREP_STRING /* max data representation length */
 #endif /* #if OMPI_PROVIDE_MPI_FILE_INTERFACE */
 
+#define MPI_MAX_DATAREP_STRING OPAL_MAX_DATAREP_STRING /* max data representation length */
+
 /*
  * MPI-2 One-Sided Communications asserts
  */