You know the drill..
Created attachment 175438 [details] Build log
Created attachment 175608 [details, diff] patches stratagus-2.2.4 for gcc43 gcc43 patching seems to be only needed with USE="-theora", so it's probably no surprise that nobody had noticed. This one-line patch fixed the issue for me on x86, just make the ebuild apply it in src_unpack.
in portage. thanks for the patch.