Add MSADPCMToPCM support to SoundEffectReader (non-DirectX)
Use using for MSADPCM readers.
Woops, merged in irrelevant changes from MG-SDL2
Merge pull request #1802 from flibitijibibo/soundeffectreader-msadpcm

Add MSADPCMToPCM support to SoundEffectReader (non-DirectX)
Merge back from upstream, another no-op.