Move the unconditional #include of net/ifq.h to the very end of file.
This seems to allow us to pass a universe with either clang or gcc
after r272244 (and r272260) and probably makes it easier to untabgle
these chained #includes in the future.
Checksum coverage values larger than 65535 for UDPLite are invalid.
Check for this when the user calls setsockopt using UDPLITE_{SEND,RECV}CSCOV.

Reviewed by: kevlo
MFC after: 3 days
Convert most BPF_TAP users to BPF_MTAP.

MFC after:	2 weeks
tty_rel_free() can be called more than once for the same tty so make sure
that the tty is dequeued from 'tty_list' only the first time.

The panic below was seen when a revoke(2) was issued on an nmdm device.
In this case there was also a thread that was blocked on a read(2) on the
device. The revoke(2) woke up the blocked thread which would typically
return an error to userspace. In this case the reader also held the last
reference on the file descriptor so fdrop() ended up calling tty_rel_free()
via ttydev_close().

tty_rel_free() then tried to dequeue 'tp' again which led to the panic.

panic: Bad link elm 0xfffff80042602400 prev->next != elm
cpuid = 1
KDB: stack backtrace:
db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame 0xfffffe00f9c90460
kdb_backtrace() at kdb_backtrace+0x39/frame 0xfffffe00f9c90510
vpanic() at vpanic+0x189/frame 0xfffffe00f9c90590
panic() at panic+0x43/frame 0xfffffe00f9c905f0
tty_rel_free() at tty_rel_free+0x29b/frame 0xfffffe00f9c90640
ttydev_close() at ttydev_close+0x1f9/frame 0xfffffe00f9c90690
devfs_close() at devfs_close+0x298/frame 0xfffffe00f9c90720
VOP_CLOSE_APV() at VOP_CLOSE_APV+0x13c/frame 0xfffffe00f9c90770
vn_close() at vn_close+0x194/frame 0xfffffe00f9c90810
vn_closefile() at vn_closefile+0x48/frame 0xfffffe00f9c90890
devfs_close_f() at devfs_close_f+0x2c/frame 0xfffffe00f9c908c0
_fdrop() at _fdrop+0x29/frame 0xfffffe00f9c908e0
sys_read() at sys_read+0x63/frame 0xfffffe00f9c90980
amd64_syscall() at amd64_syscall+0x2b3/frame 0xfffffe00f9c90ab0
Xfast_syscall() at Xfast_syscall+0xfb/frame 0xfffffe00f9c90ab0
--- syscall (3, FreeBSD ELF64, sys_read), rip = 0x800b78d8a, rsp = 0x7fffffbfdaf8, rbp = 0x7fffffbfdb30 ---

CR:		https://reviews.freebsd.org/D851
Reviewed by:	glebius, ed
Reported by:	Leon Dang
Sponsored by:	Nahanni Systems
MFC after:	1 week
Add strptime(3) support for %U and %W (take 2)

Add support for the missing POSIX-2001 %U and %W features: the
existing FreeBSD strptime code recognizes both directives and
validates that the week number lies in the permitted range,
but then simply discards the value.

Initial support for the feature was written by Paul Green.
David Carlier added the initial handling of tm_wday/tm_yday.
Major credit goes to Andrey Chernov for detecting much of the
brokenness, and rewriting/cleaning most of the code, making it
much more robust.

Tested independently with the strptime test from the GNU C
library.

PR:		137307
MFC after:	1 month
Relnotes:	yes
Change the /var dataset in the default ZFS layout to have the
ZFS property canmount=off so that /var/db/pkg and other such directories
are part of the / dataset, and only /var/mail, /var/log, and /var/crash
are excluded from the ZFS boot environment (beadm).

PR:		193971
Approved by:	jmg
MFC after:	ASAP
Relnotes:	yes
Sponsored by:	ScaleEngine Inc.
Merge remote-tracking branch 'freebsd/master' into hardened/current/chacha