While trying to build libao for the OggVorbis tools, I get the error "audio_out.c:30: header file 'dlfcn.h' not found". I've run a find to see if I could find the header, but no luck. I've tried looking up dlfcn in the man pages and found an entry with "#include <dlfcn.h>" indicating that this should work. Does anyone know how to solve this problem? Has anyone else built the OggVorbis tools for OS X?