to OS/os.h-Darwin. I have a feeling however I'm really not supposed to be #defining __GLIBC__ so there's probably a better way to get it working, but at least this works! :)
oh btw, Exim rocks.. after I got it compiled it worked right away, and I was quickly able to configure it to fit my needs. This is quite different from my experiences with sendmail, which is included with OSX in a totally broken state. :)