sys: Automated cleanup of cdefs and other formatting

Apply the following automated changes to try to eliminate
no-longer-needed sys/cdefs.h includes as well as now-empty
blank lines in a row.

Remove /^#if.*\n#endif.*\n#include\s+<sys/cdefs.h>.*\n/
Remove /\n+#include\s+<sys/cdefs.h>.*\n+#if.*\n#endif.*\n+/
Remove /\n+#if.*\n#endif.*\n+/
Remove /^#if.*\n#endif.*\n/
Remove /\n+#include\s+<sys/cdefs.h>\n#include\s+<sys/types.h>/
Remove /\n+#include\s+<sys/cdefs.h>\n#include\s+<sys/param.h>/
Remove /\n+#include\s+<sys/cdefs.h>\n#include\s+<sys/capsicum.h>/

Sponsored by: Netflix

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

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

spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD

The SPDX folks have obsoleted the BSD-2-Clause-FreeBSD identifier. Catch
up to that fact and revert to their recommended match of BSD-2-Clause.

Discussed with: pfg
MFC After: 3 days
Sponsored by: Netflix

routing: move route expiration time to its nexthop

Expiration time is actually a path property, not a route property.
Move its storage to nexthop to simplify upcoming nhop(9) KPI changes
and netlink introduction.

Differential Revision: https://reviews.freebsd.org/D35970
MFC after: 2 weeks

net: clean up empty lines in .c and .h files

* Add rib_<add|del|change>_route() functions to manipulate the routing table.

The main driver for the change is the need to improve notification mechanism.
Currently callers guess the operation data based on the rtentry structure
returned in case of successful operation result. There are two problems with
this appoach. First is that it doesn't provide enough information for the
upcoming multipath changes, where rtentry refers to a new nexthop group,
and there is no way of guessing which paths were added during the change.
Second is that some rtentry fields can change during notification and
protecting from it by requiring customers to unlock rtentry is not desired.

Additionally, as the consumers such as rtsock do know which operation they
request in advance, making explicit add/change/del versions of the functions
makes sense, especially given the functions don't share a lot of code.

With that in mind, introduce rib_cmd_info notification structure and
rib_<add|del|change>_route() functions, with mandatory rib_cmd_info pointer.
It will be used in upcoming generalized notifications.

* Move definitions of the new functions and some other functions/structures
used for the routing table manipulation to a separate header file,
net/route/route_ctl.h. net/route.h is a frequently used file included in
~140 places in kernel, and 90% of the users don't need these definitions.

Reviewed by: ae
Differential Revision: https://reviews.freebsd.org/D25067

Revert r361704, it accidentally committed merged D25067 and D25070.

* Add rib_<add|del|change>_route() functions to manipulate the routing table.

The main driver for the change is the need to improve notification mechanism.
Currently callers guess the operation data based on the rtentry structure
returned in case of successful operation result. There are two problems with
this appoach. First is that it doesn't provide enough information for the
upcoming multipath changes, where rtentry refers to a new nexthop group,
and there is no way of guessing which paths were added during the change.
Second is that some rtentry fields can change during notification and
protecting from it by requiring customers to unlock rtentry is not desired.

Additionally, as the consumers such as rtsock do know which operation they
request in advance, making explicit add/change/del versions of the functions
makes sense, especially given the functions don't share a lot of code.

With that in mind, introduce rib_cmd_info notification structure and
rib_<add|del|change>_route() functions, with mandatory rib_cmd_info pointer.
It will be used in upcoming generalized notifications.

* Move definitions of the new functions and some other functions/structures
used for the routing table manipulation to a separate header file,
net/route/route_ctl.h. net/route.h is a frequently used file included in
~140 places in kernel, and 90% of the users don't need these definitions.

Reviewed by: ae
Differential Revision: https://reviews.freebsd.org/D25067

Move route_temporal.c and route_var.h to net/route.

Nexthop objects implementation, defined in r359823,
introduced sys/net/route directory intended to hold all
routing-related code. Move recently-introduced route_temporal.c and
private route_var.h header there.

Differential Revision: https://reviews.freebsd.org/D24597