[WIP] Proper Audio/Video Dumping

Screwed up the previous PR, replacing with new PR

Old notes: https://github.com/dolphin-emu/dolphin/pull/1183
This has a potential to leak if realloc ever fails. Since realloc would return null upon failure, you would lose your only handle to the allocated data.

Normally to guard against this you would do:

```cpp
void* temp_stored_frame = realloc(stored_frame, s_bitmap.biSizeImage);

if (temp_stored_frame)
{
    stored_frame = temp_stored_frame;
}
else
{
    free(stored_frame)

    // misc error handling code after.
}
```

Is there any other way to do this that doesn't require the use of realloc?