As I belong to the people being so crazy to build their gentoo with gcc 4, I also need the -*-keyworded glibc, finding out that the latest version says:
Portage have a serious bug in regards to symlinks, and merging this with current versions will fail!
!!! ERROR: sys-libs/glibc-2.3.6 failed.
!!! Function pkg_setup, Line 1071, Exitcode 0
!!! Portage sucks.