There's no libdl on FreeBSD.
FreeBSD handles the POSIX_C_SOURCE definition very strictly - strncmp() and
a lot of other stuff isn't defined in the 2001 standards.  Thus, the functions
aren't declared when you include the library headers.

So for now don't define it; later on it may be worth figuring out which
particular standard the project is coding to and define that.
Merge pull request #106 from erikarn/freebsd-develop

There's no libdl on FreeBSD.