AUDIO: Add a hack for sample rates >65kHz.

The current audio rate code error()s out when given an input rate above 65535, so I wrote this hack for that case, which drops input samples in the linear rate converter.

This is needed for 96kHz ogg files in the AGS game The Blackwell Legacy (1.7).

Obviously it is a *hack* (and the ARM code hasn't been updated anyway), so it shouldn't be merged as-is, but I'd appreciate any thoughts/ideas/commentary.