Also fix null pointer dereference by NOT calling strlen on a possible null pointer.
* Remove assigned but not used variables (GCC 4.6) * Bump _XOPEN_SOURCE to 600, ridding of FreeBSD warnings (this probably need to be tweaked on a per-implementation basis as problems arise)
- this should make platform detection automagic - also fixes debian builds that broke in the meantime - fix osdep_darwin.c