Add IPPROTO_ICMP and IPPROTO_ICMPV6 system constants

src/unix/bsd/apple/mod.rs

src/unix/bsd/freebsdlike/mod.rs

src/unix/bsd/netbsdlike/mod.rs

src/unix/haiku/mod.rs

src/unix/notbsd/mod.rs

src/unix/solaris/mod.rs