Here is a much simpler and straight forward patch to use the bundled
copy of CELT; not sure why but this didn't work in my first attempt so
the result was the previous diff - please disregard it.
This diff simply switches from CONFIG+=no-bundled-celt to
CONFIG+=bundled-cert and therefore removes
tl;dr: drop our own port which only exists for Mumble and use the
bundeld CELT version like FreeBSD and (some) Linux distributions do.
To do so, little OpenBSD specific code is required in the CELT codec's
abstraction layers, see the patches for adding a sandboxing stub as well
as routines
