Please update elementary in portage to the latest version: 1.12.0
Newest version is now 1.12.1: https://phab.enlightenment.org/phame/live/3/post/efl_and_elementary_1_12_1_releases/
efl 1.12 is in testing, that causes elementary 1.11 fail to build.
I just added elementary-1.12.2, should be on your local rsync mirror within the next hours.