MFC: 272962

Add a new option, -P, to pkt-gen which reads a single packet from a stored
pcap file and transmits it instead of the default UDP packet.

Reviewed by:	luigi
MFC: 273279

Add new quirks for the latest Samsung SSD, model 850.

Submitted by:	sbruno
MFC r273498: MFV r273494: xz 5.0.7.
MFC r273507: Sync with NetBSD.
MFC r273619: MFV r273617: netcat from OpenBSD 5.6.
MFC r272797:

Check for mbuf copy failure when there are multiple multicast sockets

This partitular case is the only path where the mbuf could be NULL.
udp_append() checked for a NULL mbuf only after invoking the tunneling
callback. Our only in tree tunneling callback - SCTP - assumed a non
NULL mbuf, and it is a bit odd to make the callbacks responsible for
checking this condition.

This also reduces the differences between the IPv4 and IPv6 code.
MFC r272801:

Move the calls to u_tun_func() into udp6_append()

A similar cleanup for UDPv4 was performed in r220620.
MFC r272844:

Add missing UDP multicast receive dtrace probes
MFC r273703:

  Remove the ARM_DEVICE_MULTIPASS option and make its effect be the default.
MFC r268836: Fix a typo in a gpio node name.