In order to get 0AD work in Mojave we need to drop osx 10.8.
In this diff, I have to update premake scripts from 10.4 to 10.9This is an import of commit https://github.com/premake/premake-core/commit/5f57b5d62a4518f391cf66e1cfb70e4a92353178 in our premake5 alpha10 copy.
See issue https://github.com/premake/premake-core/issues/1154 for more information.