Ugly monkey patching to prevent errors with CMake (2.8.12) generated Xcode projects

An error was being thrown complaining about not recognizing the attributes refType, buildSettings and buildStyles.

Deactivating the error checking doesn't seem to cause any immediate problem. But obviously this is not a real solution, somebody who actually understands the code should have a look at it.

Signed-off-by: Carles Tomás Martí <ctm@monolito.eu>