Tests failed when presented with an interface name longer than 6 characters on OS X. Since sdl_data is variable length on OS X, and sdl_rcf and sdl_route aren't used in the library it seems sensible just to merge the structs for freebsd and os x here. Not sure if 46 is the correct maximum for sdl_data, however.
added greppable comment explaining why the struct does not match if_dl.h
remove silly println that snuck in
specify that the mismatch is only on OS X
Merge pull request #10 from moonpolysoft/os-x-long-iface-name

Tests failed when presented with iface name longer than 6 bytes