Since the upgrade of math/suitesparse to 5.2.0, it depends unconditionnaly on
math/metis. Because math/metis and math/metis-edf are conflicting, this means
that the ports which depend on SuiteSparse and on metis-edf became BROKEN.

To solve this problem, this revision adds the missings includes brought by
metis-edf to metis.

Note for myself: if everything goes well, do not forget to deprecate the port
math/metis-edf in a near future.