REDUCE_SCATTER to more thoroughly check the datatype/op combination
to see if it's valid or not. If it's not, print a meaningful error
message rather than "Invalid MPI_Op" indicating what specifically
was wrong (therefore hopefully helping users track down where in the
code the problem is, and/or telling us that there's a reduction
operation combo that we don't support that we should)
- The check for whether a datatype is intrinsic needed to be updated
-- it's not sufficient to check that dtype->id < DT_MAX_PREDEFINED;
you really need to check the PREDEFINED flag on the datatype.
Thanks to George for this fix (only intrinsics have a meaningful
value in dtype->id).
This commit was SVN r7923.