The last years this port, based on an upstream abandoned half a decade
ago, has merely seen patching and prodding by several of us, often when
it got into the way of updates of other parts of the Ports Collection.

This is the case once again with a pending update of GCC to version 8,
where we run into

gmake[2]: Entering directory '/wrkdirs/usr/ports/lang/gprolog/work/gprolog-1.4.4/src/Fd2C'
gplc -c --fast-math fd2c.pl
=>> Killing runaway build after 7200 seconds with no output

after already workarounds in place for other versions of remotely
recent compilers. Bite the bullet and mark for deprecation and
removal one-and-a-half months from now

PR: 231590