This is a simlar problem to bug #113681.
Created attachment 74259 [details, diff] Patch to avoid matching partial LINGUAS in configure
Created attachment 74260 [details] Updated ebuild.
I put this in portage while updating gconf-1.0.9 to build with gcc-4. Thanks for the patch. http://viewcvs.gentoo.org/gnome-base/gconf/files/gconf-1.0.9-gcc4.patch?rev=1.1&content-type=text/vnd.viewcvs-markup http://viewcvs.gentoo.org/gnome-base/gconf/files/gconf-1.0.9-linguas.patch?rev=1.1&content-type=text/vnd.viewcvs-markup http://viewcvs.gentoo.org/gnome-base/gconf/gconf-1.0.9.ebuild?r1=1.18&r2=1.19