Goodbye gcc, Hello clang

[Jeremy Lavergne]

Just a heads up, in Xcode 4.6.:

Deprecation of the llvm-gcc Compiler and GDB Debugger
Xcode 4.6 is the last major Xcode release that will include the llvm-gcc compiler and the GDB debugger. Please move to use the Apple LLVM compiler and LLDB debugger, and file a bug in bugreporter.apple.com for any issues that require you to use llvm-gcc or GDB.

Finally!