Created attachment 420348 [details] build.log breeze-gtk won't compile with cmake < 3.2 but doesn't depend (neither direct not indirect) on it. As cmake 2.8.12.2-r1 is still an stable option it should force cmake to >=3.2
Fixed by genstorm in https://github.com/gentoo/kde/commit/32105e05e390e617163efec811ad50f1a9536fef