at the top-level MPI API function. This allows two kinds of
scenarios:
1. MPI_Ireduce(..., op, ...);
MPI_Op_free(op);
MPI_Wait(...);
For the non-blocking collectives that we're someday planning -- to
make them analogous to non-blocking point-to-point stuff.
2. Thread 1:
MPI_Reduce(..., op, ...);
Thread 2:
MPI_Op_free(op);
Granted, for #2 to occur would tread a fine line between a correct and
erroneous MPI program, but it is possible (as long as the Op_free was
*after* MPI_reduce() had started to execute). It's more realistic
with case #1, where the Op_free() could be executed in the same thread
or a different thread.
This commit was SVN r7870.
