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)

pathchk(1): Fix the example so it allows arbitrary pathnames.

Spaces and various other characters in pathnames are not passed through
literally by xargs in its default mode. Instead, use find . -exec ... {} +

Although the -- argument is not strictly required here, add it anyway to
avoid surprises when modifying the code to find -f -somedir ...

MFC after: 1 week

pathchk: Add the new POSIX -P option.

This option checks for empty pathnames and components starting with '-'.
Our -p option also checks for the latter, which remains the case.

MFC after: 1 week

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

Sort sections.

Added the EXIT STATUS section where appropriate.

Unbreak support for systems that have no limit on pathname length.

Noticed by: bde

Update pathchk to reflect the fact that 1003.1-2001 now includes the
trailing null byte in PATH_MAX and _POSIX_PATH_MAX.

PR: 46035

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

Approved by: re

When stat(2) fails, put the name of the component it failed on in the
warning message as well as the path argument.

mdoc(7) police: tidy up the markup.

Add the pathchk utility, which checks pathnames for validity or
portability between POSIX systems.

Submitted by: Chuck Rouillard (manpage, initial implementation)