* Change the type of FIONCLEX on apple platforms from c_uint to c_ulong
* Add FIONCLEX, FIONREAD, FIOASYNC, FIOSETOWN and FIOGETOWN
  for DragonFly and OpenBSD

During the refactor in 4bd419eb, PTRACE_DETACH was accidentally removed on
these targets. This re-adds it.

Closes #1094 .

Closes #1304 .

Closes #1178.

This was added in Linux 5.1 and will only show up in the next glibc
release, thus skip in tests.