[Mpi-forum] Errata: fix obvious parameter name error

[Jeff Squyres (jsquyres)]

This was discovered after the 2-week window for the Zurich meeting.  If this can't make it into the Zurich meeting agenda, please put it on the meeting agenda for December.

It's a trivial one-word fix in the language-neutral binding for MPI_UNPACK_EXTERNAL -- needs to be applied to both the mpi-3.x and mpi-4.x branches (PR's submitted for both).  Here's the GitHub issue:

    https://github.com/mpi-forum/mpi-issues/issues/149

-- 
Jeff Squyres
jsquyres at cisco.com