https://github.com/ZDoom/ZMusic/tree/master/thirdparty In the latest upstream version, all these dependencies are bundled. In the currently packaged version, a bunch of them are and a bunch aren't: https://github.com/ZDoom/ZMusic/blob/eac26c3acac07578bb866db02c922b182aef365d/CMakeLists.txt#L217-L222 If bumping the version to the latest release, then at least fluidsynth and miniz start being newly bundled. One of the bundled libs is also the cause of bug 860117.
Thanks for the heads up.