* Port to macOS
This port to macOS is an amalgam of the existing Linux and Win32
ports. Consequently code is duplicated from each in this port:
primarily from win32 in oshw, and Linux is osal.
Synthesizing a shared common posix port, did not seem warranted given
the modest amount of code, and stable api.
This port uses the default pcap interface provided in the development
libraries shipped with XCode.
Limited testing on os releases: 10.13 and 10.14.
* fix possible race condition as for win32
See aed0f81724
* fix spelling as for linux / win32
See 7beba91c62
Marc Butler