Constructor tweaks in SAS + minor fix to end/pause flag

The memset is probably not necessary, and contradicts the constructor anyway.  Plus it has private fields so it's not pod I think?

Anyway, the rest is just an attempt to avoid uninitialized values.

Doing some initial tests on the PSP, I found that `sceSasInit()` apparently writes exactly the same data for maxVoices=1 as it does for maxVoices=32.  So then I tested `sceSasGetEndFlag()`, and it also returns `0xffffffff` on real firmware, and nothing seems to validate against `maxVoices`, just 32.

So this makes `sceSasGetEndFlag()` and `sceSasGetPauseFlag()` correct for < 32 maxVoices in `sceSasInit()`, which I've never seen used anyway...

-[Unknown]