Add AF_UNSPEC from Apple socket.h
Add AF_UNSPEC from Apple socket.h

cactorium/libc,philippkeller/libc,rust-lang-nursery/libc,rust-lang/libc,rust-lang/libc,superriva/libc,rust-lang/libc,mneumann/libc,mneumann/libc,cactorium/libc,mneumann/libc,philippkeller/libc,rust-lang-nursery/libc,cactorium/libc,superriva/libc,anatol/libc,rust-lang-nursery/libc,anatol/libc,anatol/libc,superriva/libc,philippkeller/libc