src.libnames.mk: Extend _DP_archive hack when bootstrapping on non-FreeBSD

On Linux, libcrypto is available so a non-WITHOUT_OPENSSL build happens
to work, but on macOS it isn't available to be linked against (though
there is a versioned dylib for /usr/bin/openssl etc), and neither have
libmd so would both be broken under WITHOUT_OPENSSL. Since we're using
the system libarchive, further extend the hack to ensure _DP_archive is
empty.

Fixes: ed4050750c1a ("src.libnames.mk: Add hack to workaround libarchive not being bootstrapped")
MFC after: 1 week