x11-libs/gdk-pixbuf fails to build if MAKEOPTS="-j5" is set in /etc/portage/make.conf. Workaround is to add MAKEOPTS="" to /etc/portage/env/x11-libs/gdk-pixbuf.
*** Bug 484966 has been marked as a duplicate of this bug. ***
I just hit this. I'll attach a build log.
Created attachment 358722 [details] Build failure
It looks like there are parallel build failures in other versions of this package. See bug #481372 which is the same as this bug, but that one's an unstable version while 2.26.4 is marked stable. Also see bug #368731 which is old.
*** This bug has been marked as a duplicate of bug 481372 ***