Accelerate vgm/s98 export

[jpcima]

The task is a bit slow, especially on Nuked which is heavy on the CPU.
Since we don't need the sound output, it's great if these exports can bypass the generation when they are exporting a register dump. Then, the export is going to be nearly instantaneous.

[rerrahkr]

Thanks for request. I fix export process to skip register writing to the emulation core and sample generation at 4bc08cd.

[jpcima]

Nice. Can I rewrite isNeedSampleGeneration as virtual method in ExportContainerInterface ?
The core guidelines recommend against dynamic_cast which has usually slow implementations.
Second, a future export container will be forced to think of implementing the method.

[rerrahkr]

Thanks, your idea is better than mine 😃

[jpcima]

Great 👍