Add --enable-audiotoolbox for non OS x builds

[tjayz]

build-AudioToolboxWrapper() {
  do_git_checkout https://github.com/cynagenautes/AudioToolboxWrapper.git AudioToolboxWrapper_git
  mkdir AudioToolboxWrapper_git/build
  cd AudioToolboxWrapper_git/build
	do_cmake_from_build_dir "-DCMAKE_INSTALL_PREFIX=$mingw_w64_x86_64_prefix" ..
	do_make_and_make_install
	# This wrapper library enables FFmpeg to use AudioToolbox codecs on Windows, with DLLs shipped with iTunes.
	# i.e. You need to install iTunes, or be able to LoadLibrary("CoreAudioToolbox.dll"), for this to work.
	# test ffmpeg build can use it [./ffmpeg -f lavfi -i sine=1000 -c aac_at -f mp4 -y NUL]
  cd ../..
}

  if [[ "$non_free" = "y" ]]; then
      config_options+=" --enable-nonfree --enable-libfdk-aac" 
	  config_options+=" --enable-audiotoolbox --disable-outdev=audiotoolbox --extra-libs=-lAudioToolboxWrapper" && apply_patch file://$patch_dir/AudioToolBox.patch -p1

AudioToolBox.patch works for release/7.1 untested elsewhere easy to change though.

        build_fdk-aac # Uses dlfcn.
	build-AudioToolboxWrapper # This wrapper library enables FFmpeg to use AudioToolbox codecs on Windows, with DLLs shipped with iTunes.