There are a few changes in glibc-2.10 that might make your software fail to build with it, please refer to my blog post  if you're not sure what the problem is.
And no I don't usually provide emerge --info with these bugs because they are caused by glibc-2.10!
Created attachment 196447 [details]
+ 08 Aug 2009; Samuli Suominen <firstname.lastname@example.org>
+ gchemutils-0.10.3.ebuild, +files/gchemutils-0.10.3-glibc-2.10.patch:
+ Remove invalid USE debug inherited with gnome2.eclass. Disable mozilla
+ plug-in because it needs =xulrunner-1.8* wrt #280049. Fix building with
+ GLIBC 2.10+ wrt #276298. Port from built_with_use to EAPI=2 USE deps. Fix
+ missing deps intltool and rarian.