A randomly selected unix system has a 99.999% chance of being a Linux system. Nobody cares about the other variants except for their own developers and a few historians and hobbyists.
For that matter I have no idea why you think freetype is even unix software. It builds and runs on numerous non-unix platforms.
A randomly-selected UNIX workstation has a pretty high chance of being an OSX system, I'd think. UNIX servers are 99.999% Linux, though, yes.
Surely *BSD accounts for more than 0.0001% of UNIX-like servers.
"workstation" ... "OSX"
Yeah, sure! :-)
It runs on Windows and other non-unix-like operating systems too.
It does? I remember when I was using SUA I had to build without FreeType (its build process seemed to rely heavily on building programs and then running them to produce things to build, in some way that didn't work).