The previous build method on the Pi4 uses a CMake toolchain file which assumes a 32bit ARM system.
To make it compile on ARM64, remove the toolchain file usage and add the appropriate defines/options from it to the CMake invocation.
Changed the flags so the module is only available for a Raspberry Pi that doesn't
have videocore - the RPI4 only for now.
Disabled openal support as the openal code doesn't compile currently.
