Build failure of gmp-6.2.0 on Mac Mini G4

[Charlie Kester]

(This is a copy of email sent to the port maintainer.  Re-sending to
this list in case someone familiar with powerpc has already encountered
and resolved this issue.)


I'm trying to get FreeBSD running on an old Mac Mini and have hit a snag 
with this port, which is a dependency of many others.

The configure step fails with the following output (I don't have mail 
running on the mini yet and am typing this on another machine,
so please disregard any typos.  blank lines = line breaks in output):
---------------------------------------------------------------------

===> gmp-6.2.0 depends on file: /usr/local/bin/makeinfo - found

===> Configuring for gmp-6.2.0

checking build system type... invalid configuration 
'powerpc7447-unknown-freebsd12.1': machine 'powerpc7447-unknown' not 
recognized

configure: error: /bin/sh ./config.sub powerpc7447-unknown-freebsd12.1 
failed

etc.
----------------------------------------------------------------------
I tried
# make configure CONFIGURE_ARGS=--build=powerpc7447
and
# make configure CONFIGURE_TARGET=powerpc7447

Neither worked.  Same failure.

Any suggestions on how I can resolve this issue?

-- charlie