Updated to support the latest tools and techniques (64-bit, Developer ID code signing, Xcode 5, and so on) (r. 16127581) (r. 9272790). Added support for the KAUTH_FILEOP_DELETE operation (r. 6511762).

Minor editorial change.

Work around a kernel bug by checking certain arguments for NULL.

This sample code has been to include an Xcode 2.1 project to produce universal binaries. There were no code changes required for it to run correctly on the Developer Transition Systems. However, I did modify the code slightly to eliminate some new warnings produced by GCC 4.0.