Patched libao source for OSX can be found here:
https://github.com/timonwong/libao/tree/goldendict

You can checkout the source directly using git:
  git clone -b goldendict https://github.com/timonwong/libao.git

Then, copy libao-build.sh (along with this file) to libao source directory, and build using following commands:
  chmod +x libao-build.sh
  ./libao-build.sh [goldendict source directory]