Split the sentinel library in ompi/mpi/fortran/use-mpi-f08 into
- the real sentinel that contains no code (only used to build the .mod files)
- an internal library that does contain some code
and have libmpi_usempif08.la slurp the latter.
This fixes a regression introduced in open-mpi/ompi@5de5e751ed
Signed-off-by: Gilles Gouaillardet <gilles@rist.or.jp>
01fe53d531