OK it look like gog have renamed winmm.dll to _winmm.dll
So if you want to re-enable playing back the music from .ogg files it would seem that you need to do the following.
1. Mount the CDIMAGE game.gog with daemon tools or cd emulation software of choice.
2. rip tracks2 - track11 with CDEx (or other ripping software of choice) as ogg the "music" folder inside your gog quake folder as Track02.ogg - Track11.ogg
3. rename _winmm.dll to winmm.dll
4. run qlquake as normal from the icon and enjoy the music.
A little further tweaking will be and ripping the music from the expansion images will be required to get them playing the correct music but that should not be to hard.
The same ogg music files also work with quakespasm and it will automatically play the right music if you follow the instructions in Quakespasm-Music.txt
Its good to finally have a legal way to purchase Quake with the expansions and get all the music :-)
If people are still stuck I am sure if would not be that hard to create a .bat file that automatically rips the music from the iso images and saves it in the right place, now we know the required steps to make things work. But I don't have time to look at that at the moment.
This worked perfectly for me, thank you!.