MFC r267667:
use .Mt to mark up email addresses consistently (part1)

PR: 191174
Submitted by: Franco Fichtner <franco at lastsummer.de>

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

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

Raise WARNS for various tools where possible.

Submitted by: Marius Nünnerich <marius@nuenneri.ch>

Fix malloc size (visible on amd64, with "kldconfig -r").

Sync program's usage() with manpage's SYNOPSIS.

Added the EXIT STATUS section where appropriate.

Make NULL a (void*)0 whereever possible, and fix the warnings(-Werror)
that this provokes. "Wherever possible" means "In the kernel OR NOT
C++" (implying C).

There are places where (void *) pointers are not valid, such as for
function pointers, but in the special case of (void *)0, agreement
settles on it being OK.

Most of the fixes were NULL where an integer zero was needed; many
of the fixes were NULL where ascii <nul> ('\0') was needed, and a
few were just "other".

Tested on: i386 sparc64

Use __FBSDID() to quiet GCC 3.3 warnings.

style(9): use NULL when assigning/comparing a char *,
consitently compare fileid with 0 using == and !=.

Reviewed by: silence on @audit

These are WARNS=5 clean, mark them as such to keep them that way.

Look at by: sebastian.ssmoller@web.de on audit@

s/filesystem/file system/g as discussed on -developers

The .Nm utility

Default to WARNS=2.
Binary builds that cannot handle this must explicitly set WARNS=0.

Reviewed by: mike

This is actually making its enterance in FreeBSD 4.4.

mdoc(7) police: cosmetics.

Properly cast a size argument to an unsigned type.

Thanks to: dd for noticing the need for a cast.

Silence warnings on the Alpha: don't assume size_t is an int.

Add kldconfig(8), a utility to modify the kernel module search path.

Reviewed by: -arch, -audit