sys: Remove $FreeBSD$: one-line .c pattern

Remove /^[\s*]*__FBSDID\("\$FreeBSD\$"\);?\s*\n/

jail: convert several functions from int to bool

these functions exclusively return (0) and (1), so convert them to bool

We also convert some networking related jail functions from int to bool
some of which were returning an error that was never used.

Differential Revision: https://reviews.freebsd.org/D29659
Reviewed by: imp, jamie (earlier version)
Pull Request: https://github.com/freebsd/freebsd-src/pull/663

sysent: Get rid of bogus sys/sysent.h include.

Where appropriate hide sysent.h under proper condition.

MFC after: 2 weeks

jail: network epoch protection for IP address lists

Now struct prison has two pointers (IPv4 and IPv6) of struct
prison_ip type. Each points into epoch context, address count
and variable size array of addresses. These structures are
freed with network epoch deferred free and are not edited in
place, instead a new structure is allocated and set.

While here, the change also generalizes a lot (but not enough)
of IPv4 and IPv6 processing. E.g. address family agnostic helpers
for kern_jail_set() are provided, that reduce v4-v6 copy-paste.

The fast-path prison_check_ip[46]_locked() is also generalized
into prison_ip_check() that can be executed with network epoch
protection only.

Reviewed by: jamie
Differential revision: https://reviews.freebsd.org/D33339

Move most of the contents of opt_compat.h to opt_global.h.

opt_compat.h is mentioned in nearly 180 files. In-progress network
driver compabibility improvements may add over 100 more so this is
closer to "just about everywhere" than "only some files" per the
guidance in sys/conf/options.

Keep COMPAT_LINUX32 in opt_compat.h as it is confined to a subset of
sys/compat/linux/*.c. A fake _COMPAT_LINUX option ensure opt_compat.h
is created on all architectures.

Move COMPAT_LINUXKPI to opt_dontuse.h as it is only used to control the
set of compiled files.

Reviewed by: kib, cem, jhb, jtl
Sponsored by: DARPA, AFRL
Differential Revision: https://reviews.freebsd.org/D14941

Allow explicitly assigned IPv4 loopback address to be used in jails

If a jail has an explicitly assigned loopback address then allow it to be
used instead of remapping requests for the loopback adddress to the first
IPv4 address assigned to the jail.

This fixes issues where applications attempt to detect their bound port
where they requested a loopback address, which was available, but instead
the kernel remapped it to the jails first address.

A example of this is binding nginx to 127.0.0.1 and then running "service
nginx upgrade" which before this change would cause nginx to fail.

Also:
* Correct the description of prison_check_ip4_locked to match the code.

MFC after: 2 weeks
Relnotes: Yes
Sponsored by: Multiplay

Move IPv4-specific jail functions to new file netinet/in_jail.c
_prison_check_ip4 renamed to prison_check_ip4_locked

Move IPv6-specific jail functions to new file netinet6/in6_jail.c
_prison_check_ip6 renamed to prison_check_ip6_locked

Add appropriate prototypes to sys/sys/jail.h

Adjust kern_jail.c to call prison_check_ip4_locked and
prison_check_ip6_locked accordingly.

Add netinet/in_jail.c and netinet6/in6_jail.c to the list of files that
need to be built when INET and INET6, respectively, are configured in the
kernel configuration file.

Reviewed by: jtl
Approved by: sjg (mentor)
Sponsored by: Juniper Networks, Inc.
Differential Revision: https://reviews.freebsd.org/D6799