Bug#961183: metis: providing a 64-bit build

[Drew Parsons]

Package: metis
Followup-For: Bug #961183

Hi Fred, I guess the simple reason why there's no pkgconfig for Metis
is that upstream does not provide one.

We could add one ourselves easily enough.  But SCOTCH-Metis
compatibility would want to be taken into consideration.  Historically
SCOTCH-Metis never had full compatibility (#506033, #653647), but
they're about to make a new release expected to address that.