Fortran: put type(c_ptr) interfaces in a separate file in the TKR mpi module

Older gfortran compilers (e.g., the gfortran that ships in RHEL5) do
not support ISO_C_BINDING, and therefore do not support the
TYPE(C_PTR) type.  As such, they cannot support the overloaded
interfaces for MPI_WIN_ALLOCATE_SHARED and MPI_SHARED_QUERY that are
mandated in MPI-3.

So we separate those interfaces out into a separate .F90 file that is
#include'd in the tkr mpi.F90 file.  In this separate .F90 file, we
use an #if to determine whether the compiler supports ISO_C_BINDING or
not.

Also re-jiggered the order of testing in ompi_setup_mpi_fortran.m4: we
now need to test whether the compiler supports ISO_C_BINDING even when
we're only building the mpi module (not strictly when we're building
the mpi_f08 module).

Finally, tweaked the use-mpi-tkr/Makefile.am to:

* Add some proper dependencies for mpi.F90
* Allow the general AM compilation to be used instead of supplying a
  specific rule for compiling mpi.F90

cmr=v1.8.2:ticket=#4736
build: remove distro id from src.rpm filename, select md5 packing algorithm for
consistency across different distros: src.rpm create on one distro can be unpacked on
another when same packing algorithm used on both.

reviewed by Jeff
cmr=v1.8.2:reviewer=ompi-rm1.8
Fix one spot missed by recent commit