Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Backport just the sys/{dev,modules}/cxgb{,e}/ parts of r237263, and then
disable the TOE and iWARP modules in the Makefiles (they won't compile
without the rest of r237263).

This reduces diffs between the cxgb/cxgbe drivers in head and 9 and
makes it easy to MFC other fixes to 9.

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

Remove opt_mac.h generation for various kernel modules that no longer
require it.

Submitted by: pjd

Update cxgb include paths to not require prefixing with dev/cxgb

Submitted by: Chelsio Inc.

move cxgb_lt2.[ch] from NIC to TOE
move most offload functionality from NIC to TOE
factor out all socket and inpcb direct access
factor out access to locking in incpb, pcbinfo, and sockbuf

- update firmware to 5.0
- add support for T3C
- add DDP support (zero-copy receive)
- fix TOE transmit of large requests
- fix shutdown so that sockets don't remain in CLOSING state indefinitely
- register listeners when an interface is brought up after tom is loaded
- fix setting of multicast filter
- enable link at device attach
- exit tick handler if shutdown is in progress
- add helper for logging TCB
- add sysctls for dumping transmit queues

- note that TOE wxill not be MFC'd until after 7.0 has been finalized

MFC after: 3 days

Don't overload tcp_usrreqs unless the kernel doesn't provide offload support.

Make TCP offload work on HEAD (modulo negative interaction between sbcompress
and t3_push_frames).
- Import latest changes to cxgb_main.c and cxgb_sge.c from toestack p4 branch
- make driver local copy of tcp_subr.c and tcp_usrreq.c and override tcp_usrreqs so
TOE can also functions on versions with unmodified TCP

- add cxgb back to the build

Makefile for the TCP offload module