Don't write loop context for DSPs when not looped
Don't write loop context for DSPs when not looped

When BRSTM files aren't looped, the loop context is a duplicate of the starting context. With DSPs, however, the loop context should be empty if the file doesn't loop.

Thealexbarney/LibDspAdpcm,Thealexbarney/LibDspAdpcm,Thealexbarney/VGAudio,Thealexbarney/VGAudio