Remove the CMSG_ APIs from bitrig

src/unix/bsd/netbsdlike/mod.rs

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

src/unix/bsd/netbsdlike/openbsdlike/bitrig/x86.rs

src/unix/bsd/netbsdlike/openbsdlike/bitrig/x86_64.rs

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