deprecate and eventually delete MPI_F_STATUS_IGNORE and related #1092
Description
Problem
#837 describes the relatively low utility of these. Tools can implement a solution without them and apparently do, for some reason.
These are unimplementable in the standard ABI, because of MPI_Fint, which is why they are already absent there.
Proposal
Deprecate MPI_F_STATUS_IGNORE, MPI_F_STATUSES_IGNORE, MPI_F08_STATUS_IGNORE and MPI_F08_STATUSES_IGNORE.
Changes to the Text
Note deprecation in Chapter 19. Remove the relevant text when deleting is possible.
Impact on Implementations
These are annoying to implement because they force the C API definition to know about Fortran. They are already absent from the standard ABI for this reason.
Impact on Users
It is unclear if anyone needs these, but if they do, they are tools implementers who have workarounds.