Audio channels not always cut off on rewind

[NarryG]

In certain games (Mario & Luigi Superstar Saga being the example I have), it appears that rewind isn't properly cutting off certain audio channels.

This issue exists in both the 0.6.x branch (including 0.6.3 stable) as well as the 0.7.x branch

Here's a clip demonstrating the issue:
https://streamable.com/muc4b

[endrift]

Can reproduce. Channel 3 is the faulty one here.

[NarryG]

Could this be backported to 0.6.X so it can be merged into Bizhawk?

[endrift]

Yup, though hopefully 0.7 comes out soon so they can adopt it.

[endrift]

Done.