Forgotten MPI_Status_set_elements_c

[martinruefenacht]

Problem

The Embiggenment missed the introduction of MPI_Status_set_elements_c.

This was noted by a user of MPICH: pmodels/mpich#5413

Proposal

Correctly introduce the required embiggened procedure.

Changes to the Text

An additional language expression.

Impact on Implementations

Need to implement another procedure.

Impact on Users

Can use an embiggened version of the procedure.

[Wee-Free-Scot]

In addition to adding the [_C] embiggened interface, the text describing MPI_STATUS_SET_ELEMENTS[_X|_C] needs to mention MPI_GET_ELEMENTS_C and MPI_GET_COUNT_C when listing the query procedures.

This is an opportunity to replace the inline code with simple \mpifunc references -- i.e. remove the argument list, which seems to be entirely superfluous (p 641, lines 29-31).

[wgropp]

+1 on using mpifunc and removing arg lists from inline text

[martinruefenacht]

@Wee-Free-Scot I removed the parameter lists, but they were already using mpifunc. No mention of _x in the text anymore. Is this better?

[wesbland]

This passed an errata vote on 2021-09-10:

Yes	No	Abstain
29	0	1