GLEP67. The alias was created mostly as 'help' for people having trouble with clang builds, so I guess I'll just make sys-devel/clang maintained by llvm people. Especially that nowadays it's just a meta-ebuild.
commit 6e41b746a78f67f6cf771b2b373c2e8848c43e68 Author: Michał Górny <mgorny@gentoo.org> Date: Tue Dec 29 23:55:46 2015 sys-devel/clang: Copy maintainers from sys-devel/llvm clang@ serves mostly as support address, and the actual LLVM binaries are provided by sys-devel/llvm anyway.