fortran: fix the MPI_SIZEOF problems in the Fortran interfaces

This PR is the union of several commits on master; I squashed them
down to a single commit here, for simplicity.

Refs open-mpi/ompi#198
.gitignore: rename .gitignore_global and add in new Fortran ignores
Merge pull request #3 from jsquyres/topic/fortran-sizeof-fixes

fortran: fix the MPI_SIZEOF problems in the Fortran interfaces
RM-approved