Define additional IPPROTO_* constants.

src/unix/bsd/apple/mod.rs

src/unix/bsd/freebsdlike/dragonfly/mod.rs

src/unix/bsd/freebsdlike/freebsd/mod.rs

src/unix/bsd/netbsdlike/netbsd/mod.rs

src/unix/bsd/netbsdlike/openbsdlike/mod.rs

src/unix/notbsd/linux/mod.rs

src/unix/notbsd/mod.rs

src/unix/uclibc/mod.rs