Add ptrace for non-apple BSDs

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

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

src/unix/bsd/freebsdlike/mod.rs

src/unix/bsd/netbsdlike/mod.rs

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

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