boost: add patch for boost::atomic when compiled with LLVM 3.4

Adding two patches for boost::atomic to fix the compilation errors, which occur with LLVM 3.4 on OS X 10.9 with Xcode 5.1.
It is fixed already in boost --HEAD but until either boost 1.56.0 or 1.55.1 (?) is out and contains a fix, we probably have to patch this.
Best regards, Clemens

Should fix https://github.com/Homebrew/homebrew/issues/27396