Fix auvaltool bad max frames error

[1ci]

Fixes the following error when you run the AU validation tool:

Bad Max Frames - Render should fail
ERROR: Input asked for more frames (8192) than current max frames setting (512)
ERROR: AudioUnitRender should have returned an error for too many frames but returned noErr

[1ci]

Forgot to mention. This also fixes the following:

Slicing Render Test at 64 frames
ERROR: Input IOData's Buffer Sizes do not match inNumFrames count
ERROR: Render Input returned an error, but was not returned to the caller of AURender

[scheffle]

Hi @1ci, I just tried to reproduce the auval error, but I wasn't able to do so. How do I check the error without your patch?