Add -fPIC for amd64, this will help CalculiX build on amd64 when the
atlas libraries are not build statically. For now a shared library, and
therefore a run dependency to the ports that build with metis, is not
convenient.

Since I'm there, fix MASTER_SITES.

PR: 93714
Submitted by: Pedro F. Giffuni <giffunip (at) asme.org>