I have installed the "Command Line Tools for Xcode" for OS X, which provides a minimal command-line build environment on OS X. They are available here:

http://developer.apple.com/downloads

If you only install these tools and attempt to compile libsndfile, compilation fails in sndfile-play.c as it references Carbon.h, which is not included with these tools.

Carbon.h is not required, and sndfile-play.c compiles fine if you remove it.