Re: [PATCH 0/1] MR5647: xaudio2/tests: Fix test failures with xaudio2_8 in test_submix().

[Paul Gofman (＠gofman)]

xaudio2_8 tests started failing on Windows since commit b928f0eb08da9a10dae3cb7b33ec16b164a2fddd ("xaudio2: Use FAudioVoice_DestroyVoiceSafeEXT() in destroy_voice().").

Apparently xaudio 2.8 has improved validation:
 - IXAudio2SubmixVoice_SetOutputVoices() fails if the output voice doesn't have ProcessingStage greater than source voice;
 - IXAudio2SubmixVoice_SetOutputVoices() fails if pSendList have zero SendCount in XAUDIO2_VOICE_SENDS but non-NULL pSends.