dosbox-x

add dosbox.conf option to enable or disable the dc bias adjustment code

Mixer: When mixing all channels into the final output, apply DC bias correction so that games like In Extremis do not cause distortion in other mixer channels and with the overall audio mix in the user's operating system, for example, playing a DOS game like In Extremis while listening to a YouTube video

Mixer: Hold last sample in render if nothing rendering, to avoid pops

Disney sound source fix shutdown

Merge pull request #6310 from maron2000/osfree_test