[Mpi-forum] Errata reading: add missing "const" into two C bindings

Two in a single day: announcing another all-new, exciting errata item! https://github.com/mpi-forum/mpi-issues/issues/307 The C bindings for MPI_STATUS_F082C and MPI_STATUS_C2F08 are missing "const". 3.x and 4.0 PRs and PDFs are attached to the issue. Enjoy! -- Jeff Squyres [email protected]