Linux 3.12.51 was released on 2015-11-25.
https://gitweb.gentoo.org/proj/linux-patches.git/commit/?h=3.12&id=bad9a9b028f0c1856a85bc1b0414854fee73090c https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=d10f98e80e8d06bfee2d90e9d0aeac5c6ca1cf83