Per MPI-2 ballot 3, the definition of MPI::BOTTOM has changed. w00t!

Fixes trac:1175.

This commit was SVN r17850.

The following Trac tickets were found above:
  Ticket 1175 --> https://svn.open-mpi.org/trac/ompi/ticket/1175

ompi/mpi/cxx/constants.h

@@ -54,7 +54,7 @@ OMPI_DECLSPEC extern const int ERR_WIN;
 
 
 // assorted constants
-OMPI_DECLSPEC extern const void* BOTTOM;
+OMPI_DECLSPEC extern void* const BOTTOM;
 OMPI_DECLSPEC extern const void* IN_PLACE;
 OMPI_DECLSPEC extern const int PROC_NULL;
 OMPI_DECLSPEC extern const int ANY_SOURCE;

ompi/mpi/cxx/mpicxx.cc

@@ -52,7 +52,7 @@ int mpi_errno = MPI_SUCCESS;
 #endif
 
 
-const void* BOTTOM = (void*) MPI_BOTTOM;
+void* const BOTTOM = (void*) MPI_BOTTOM;
 const void* IN_PLACE = (void*) MPI_IN_PLACE;
 
 // return  codes