Drats. The 5.3.0 and 6.1.0 GCC patches are incomplete for ABIv0, because they don't add support the "-newclib" switch, so the compilation fails before everything gets built. I somehow still have the SDK libs/includes, but I forgot to put in the contrib sources, and now it refuses to build it separately. I guess I'll try 4.8.3 which has this switch, and according to the GCC site has a feature complete C++11 implementation.