I've been able to build gnustep-libs on x86; the ebuild currently has KEYWORDS="~ppc" set Perhaps ~x86 can be added to the KEYWORDS in this ebuild?
This depends on the problem I described in #111378 being resolved, and I'm pretty sure this ebuild will suffer from the same problem since its pulling from CVS as well. You can open the bug back up after those issues have been resolved and I'll be happy to add ~x86 to them. How the ebuild is currently it will fail on any system that doesn't have userpriv or usersandbox, but has sandbox set, not a very good candidate for stable in that condition.