Plase place the check for gcc-4 anywhere else then in pkg_setup (I would prefer pkg_compile). Currently you can not "emerge --usepkg qemu-softmmu" on a computer that does not have gcc-3 merged. And please consider adding gcc-3 as a buildtime dep, or alter something other not making emerge --depclean remove gcc-3 by default, as currently you can't recompile it if you have installed gcc-4.3.
qemu-0.10 doesn't have such check anymore
