- Copy stable/10 (r259064) to releng/10.0 as part of the
10.0-RELEASE cycle.
- Update __FreeBSD_version [1]
- Set branch name to -RC1

[1] 10.0-CURRENT __FreeBSD_version value ended at '55', so
start releng/10.0 at '100' so the branch is started with
a value ending in zero.

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

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

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

The number after the command is *not* optional.

MFC after: 1 day

The output of perror(1) is now showing local messages for locales
supported by libc/nls

PR: bin/140499
Approved by: gnn@

Use prototype for usage(). This makes perror(1) WARNS=6 clean.

Approved by: gnn

A few more style changes as well as a more broad allowance for
errors to be given by the caller. Change output to be easier
for use in scripts.

Submitted by: bce

o style.Makefile(5): remove SRCS.

Fix a few style(9) nits.

Submitted by: danfe

Add a new program, perror, which takes an errno as a command line argument
and outputs the associated textual message in the same way that
perror(3) would if called within a program.