AC97 audio delays under stress

[Paul17041993]

When the VM is stressed in some way, commonly via running a game, the audio ends up with a major delay (~1000-2000ms) and mild choppy-ness. Unknown if this affects the HD and SB16 audio devices as both are non-functional for the used guests.

Tested to occur with windows xp (32b) and 2k guests, the 2k guest also cannot use audio acceleration at all as it results in a lack of audio on many formats. Host is windows 10 x64, consistent with different audio devices and Hyper-V enforced.

[pentagonik]

Please retry with latest 5.2.