/etc/env.d is a Gentoo-specific directory to define default env vars for user sessions. It's not a feature of clang to read that directory, so it's not correct

/etc/env.d is a Gentoo-specific directory to define default env vars for user sessions. It's not a feature of clang to read that directory, so it's not correct to assume other distros would have it. It's just that Gentoo's compiler setup reads the CTARGET env var to select the target, and Gentoo uses /etc/env.d to set it.