Usual info text: Ruby upstream have now officially deprecated the Ruby 1.8 branch, there will be no more updates. This means it is time for us to update packages that have exclusively been built on Ruby 1.8 to use Ruby 1.9. This could be as easy as defining USE_RUBY="ruby19" instead of ruby18, but might require more work or patches for (mostly older) packages with 1.9 compatibility issues. Feel free to ask in #gentoo-ruby if you have any questions. In your case, I guess you could just remove the 2.1.9-r2 version, as the others seem to build for 1.9 as well.
<sys-libs/libselinux-2.1.12 have been removed from the tree.