sys: Remove $FreeBSD$: one-line sh pattern

Remove /^\s*#[#!]?\s*\$FreeBSD\$.*$\n/

modules: a lot: need opt_kern_tls.h

This fixes the standalone build.

sys/modules: normalize .CURDIR-relative paths to SRCTOP

This simplifies make output/logic

Tested with: `cd sys/modules; make ALL_MODULES=` on amd64
MFC after: 1 month
Sponsored by: Dell EMC Isilon

Remove unnecessary inclusions of bsd.own.mk.

A new jail(8) with a configuration file, to replace the work currently done
by /etc/rc.d/jail.

Import the Statistical Information For TCP Research (SIFTR) kernel module into
FreeBSD. SIFTR logs a range of statistics on active TCP connections to a log
file, providing the ability to make highly granular measurements of TCP
connection state. The tool is aimed at system administrators, developers and
researchers alike. Please take it for a spin and test it out - the man page
should have all the information required to get you going.

Many thanks go to the Cisco University Research Program Fund at Community
Foundation Silicon Valley and the FreeBSD Foundation. Their support of our work
at the Centre for Advanced Internet Architectures, Swinburne University of
Technology is greatly appreciated.

Sponsored by: Cisco URP, FreeBSD Foundation
Reviewed by: dwmalone, gnn, rpaulo
Tested by: Many on freebsd-current@ and elsewhere over the years
MFC after: 1 month