Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

Obviously the option is known as COMPAT_LINUX32 on amd64.

PR: docs/149182
Pointed out by: Fernando <fernando.apesteguia at gmail.com>
MFC after: 3 days

Update .Dt on these man pages: the kernel modules and corresponding man
pages are installed on more platforms than just i386.

Move man pages out of man4.i386. Most of them are applicable to amd64
too, so, instead of descending to the i386 directory, we add some magic to
the parent Makefile.
These man pages refer to drivers that I'm aware that work on amd64. Most
likely there are more, but I'll deal with them later.

Approved by: brueffer, philip, takawata

Use a standard section 4 SYNOPSIS.

MFC after: 3 days

Markup fixes.

2 spelling fixes...

Noticed by: John E Hein <jhein@timing.com>

- xref linsysfs
- improve the ldconfig part
- tell about pitfalls with the osrelease sysctl

Remove kern.elf32.can_exec_dyn sysctl. Instead extend Brandinfo structure
with flags bitfield and set BI_CAN_EXEC_DYN flag for all brands that usually
allow executing elf dynamic binaries (aka shared libraries). When it is
requested to execute ET_DYN elf image check if this flag is on after we
know the elf brand allowing execution if so.

PR: kern/87615
Submitted by: Marcin Koziej <creep@desk.pl>

-mdoc sweep.

Briefly document the use of kern.elf32.can_exec_dyn.

MFC after: 3 days

Uniformly refer to a file system as "file system".

Approved by: re

More file system > filesystem

Prepare for mdoc(7)NG.

Fix broken cross-reference to linprocfs(5).

Replace the thumb-suck phrase "system call vector translation" with
something that people who like tomato juice prefer.

Import the new linux(4) manual page, which will be useful when the
linux(8) utility and manual page go away.