The static-libs USE flag is missing. SDL_STATIC is just set to no.
Created attachment 926192 [details] My own fix
This is intentional, removed in [1] -- see also [2]'s "Packages must not install static libraries unless they are explicitly required, either by themselves or their reverse dependencies", adding IUSE=static-libs is only done when there is a specific reason to. [1] https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=e1dd2ba46c51 [2] https://projects.gentoo.org/qa/policy-guide/installed-files.html#pg0302