The 4.9 series kernel will not link with gold without patches
needs this patch too https://lists.ubuntu.com/archives/apparmor/2016-October/010158.html
This bug does not affect the 4.11 branch, which is now in tree. Furthermore gentoo-sources has the same issue for branch 4.9, and is thus not patched. Letting rt-sources be in the same situation is sane, I think. If you care about getting rt-source-4.9* to link with gold, then you should first file a bug against gentoo-sources. If the maintainers adopt a fix, then I can carry it out for rt-sources.