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.
Created attachment 917854 [details] [New ebuild] media-libs/zmusic-9999.ebuild with multilib and git support (works by copying for 1.1.4-r1 too
This ticket is about using bundled library dependencies. Your proposed ebuild doesn't appear to affect that in any way so it would be best to create an entirely different ticket about updating the version.
Comment on attachment 917854 [details] [New ebuild] media-libs/zmusic-9999.ebuild with multilib and git support (works by copying for 1.1.4-r1 too obsolete by https://bugs.gentoo.org/949024