[xcode] - finally fix the last pieces which were forgotten during xcode ...

...project merge. Now we really use the stuff from tools/darwin/Configurations/ for all platforms and targets. And we got rid of the last hardcoded shit in the project. From now on we only alter the xcconfig files when we add new libraries or compiler defines ...

Ha i found the bastards @davilla && @jmarshallnz

*jumps in circles*