Belatedly remove the vinum(4) manual page. The vinum
manager is absent in FreeBSD since 6.0-RELEASE.

Reviewed by:	joel
Contrary to what the deleted comment said, the m_move_pkthdr()
will not smash the M_EXT and data pointer, so it is safe to
pass an mbuf with external storage procuded by m_getcl() to
m_move_pkthdr().

Reviewed by:	andre
Sponsored by:	Nginx, Inc.
- Replace compat macros with function calls.
- Remove superfluous cleaning of m_len after allocating.

Sponsored by:	Nginx, Inc.
- Replace compat macros with function calls.
Hide version string under verbose.

Approved by:	mav
Remove reference to vinum(4). The manual page was removed in r248370.
Cross-reference gvinum(8) instead of vinum(8).
Style: Remove redundant space.
Style: Whitespace fixes.
Fix version in the .Fx macro.

Reported by:	<deeptech71@gmail.com>
Allow vmm stats to be specific to the underlying hardware assist technology.
This can be done by using the new macros VMM_STAT_INTEL() and VMM_STAT_AMD().
Statistic counters that are common across the two are defined using VMM_STAT().

Suggested by:	Anish Gupta
Discussed with:	grehan
Obtained from:	NetApp
Add a note to the HISTORY section about lchflags(2) being introduced in
FreeBSD 5.0.
Fix the '-Wtautological-compare' warning emitted by clang for comparing the
unsigned enum type with a negative value.

Obtained from:	NetApp
Add a couple of examples.

Obtained from:	OpenBSD
The mode argument for open(2)/openat(2) only makes sense if the O_CREAT flag
was given.

Sponsored by:	The FreeBSD Foundation
Add __aeabi_memset to libkern, implemented using memset, as clang may
generate calls to it.
Update the tests now that absence of the O_APPEND flag requires CAP_SEEK
capability. Add some more tests.

Sponsored by:	The FreeBSD Foundation
Require CAP_SEEK if both O_APPEND and O_TRUNC flags are absent.

In other words we don't require CAP_SEEK if either O_APPEND or O_TRUNC flag is
given, because O_APPEND doesn't allow to overwrite existing data and O_TRUNC
requires CAP_FTRUNCATE already.

Sponsored by:	The FreeBSD Foundation
The -mno-apcs-frame argument is unavaliable on clang, also ignore it there.
Link libgcc_s against compiler-rt on ARM EABI. This allows us to use all of
the symbols in compiler-rt, including the ones not available in the old
libgcc. This fixes the build with clang which generates calls to funstions
that are missing from libgcc_s.