Ok this is getting stupid, configure scripts suck. bug 3135, bug 3137, and this one all fix the same type of stupidity in configure scripts that get gcc-3 include directory search order warnings while checking for headers and therefore decide that they can't find the header file... I hope that there is some sort of a general fix for this, but if not I'll just keep making this petty little fixes and shoot myself tomorrow. Note, these fixes in general may or may not work on systems other than gentoo, as they take out some of configure's autodetecting folder stuffs... but on gentoo systems of all compiler versions this should work fine.
Tested on various systems and committed
