OpenDNSSEC on OS X

Configuration works with gcc (I didn't try with clang but as it is a system include issue it should be the same) if and only if I add:
-D_POSIX_C_SOURCE in CFLAGS in the configuration phase.
BTW as it is a standard flag and already managed in configure[.ac] it should be possible (or even easy) to handle OS X in configure[.ac].
Note I use OpenDNSSEC only for the ods-hsm* tools so I can't say if it fully works (but I can run a test suite if you'd like).
I've attached configure and make logs with config.log and config.status files.