pcap_open_dead(3pcap) on macOS

The text 5380be3f541e, as macOS 10.14.6, macOS 10.12.3, macOS 10.12.2, macOS 10.12.1, macOS 10.12 shipped it.

open a fake pcap_t for compiling filters or opening a capture for output

pcap_open_dead(3pcap) on macOS now