cmake -G "Visual Studio 12" -H. -Bbuild -DLOVE_MPG123=OFF
Duplicate of #404.
It's weird this was not in the cmake file, but the patch seems sane, I'll import it.
Previous patch looks outdated and doesn't work as expected. Now only CMakeList.txt needs to be modified to make mpg123 optional.
Also, double new line sneaked in with the patch. I didn't really expect it to be added as is ;).