This diff builds Python --with-system-libmpdec, using libmpdec-2.5.1 from ports.
mpdecimal-2.5.1 is very well tested, since I had access to a large compile
farm with a broad variety of architectures in the past 6 months. It is compatible with _decimal.c in Python-3.7, except for trivial build patches
that are due to cleanups in mpdecimal.h.
There are no new warnings in ``portlint -A''.
Created attachment 222538 [details]