Remove $FreeBSD$: two-line nroff pattern

Remove /^\.\\"\n\.\\"\s*\$FreeBSD\$$\n/

netmap: pkt-gen: sync with upstream

Keep in sync with the recent upstream changes:

Fix compilation on 32-bit architectures
Update IP length, UDP length/checksum when size changes
Man page fixes

Submitted by: jlduran@gmail.com
MFC after: 7 days
Differential Revision: https://reviews.freebsd.org/D39760

netmap: bridge, pkt-gen: fix man page typo

Reported by: ian
MFC after: 3 days

netmap: minor documentation fix

Also update date of pkt-gen.8 (not done in r366387).

Submitted by: milosz.kaniewski@gmail.com
MFC after: 3 days

netmap: pkt-gen: minor corrections to documentation

Submitted by: Brian Poole <brian90013@gmail.com>
MFC after: 3 days

netmap: pkt-gen: several updates from upstream

Various improvements to the netmap pkt-gen program:

- indentation fixes
- support for IPV6
- fixes to checksum computation
- support for NS_MOREFRAG
- rate limiting in ping mode

Reviewed by: bcr, 0mp
Approved by: gnn (mentor)
MFC after: 3 days
Differential Revision: https://reviews.freebsd.org/D17698

netmap: add man page for the bridge program

Added bridge(8).
Also, minor fixes to the netmap "bridge" application:
- indentation fixes and code cleanup
- better usage description
- better processing of netmap flags

Reviewed by: 0mp
Approved by: gnn (mentor)
MFC after: 3 days
Differential Revision: https://reviews.freebsd.org/D17664

Add a manual page for pkt-gen.

Sponsored by: EMC / Isilon Storage Division