meson: Implement getopt logic from autoconf
Not replacing getopt/getopt_long definitely causes issues on mingw. It's not
as clear whether the solaris & openbsd aspect is still needed, but if not, we
should remove it from both autoconf and meson.
Discussion: http://postgr.es/m/
20220928022724.erzuk5v4ai4b53do@awork3.anarazel.de