Created attachment 451592 [details] build.log With sys-devel/flex-2.6.1 it builds succesfully
Created attachment 451594 [details] emerge -pqv qtwebkit
Created attachment 451596 [details] emerge --info
I can confirm this bug, which goes away when flex 2.6.2 is masked. Seems likely related to Bug 598244, which documents a similar problem building wine. https://bugs.gentoo.org/show_bug.cgi?id=598244
This is fixed with flex-2.6.3: commit 2601a5c0e5304ddb0b9b1d608b5b12ce04dc3a90 Author: Lars Wendler <polynomial-c@gentoo.org> Date: Fri Dec 30 22:18:40 2016 sys-devel/flex: Bump to version 2.6.3 Removed completely broken 2.6.2 version. Package-Manager: Portage-2.3.3, Repoman-2.3.1