mac: allow cross compiling with host/build x86_64-apple-macos
apple silicon supports to cross compile without special build-tools/full
cross-compiling setup, so just always pass the build/host for firebird.
firebird and nss don't recognize the -macos specifier, so substitute it
by -darwin to make those happy…
Change-Id: I953317fc87da2a20dc91acd88c8528796c3b2a69
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/110093
Tested-by: Jenkins
Reviewed-by: Christian Lohmaier <lohmaier+LibreOffice@googlemail.com>