- 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

Provide SWIDTH information so that applications like tcsh(1) can properly
handle with zh_CN.GBK locale, which is quite common for users who uses
Simplified Chinese.

MFC Candidate.

Add zh_CN.GBK

PR: 51504
Submitted by: Statue <statue@freebsd.sinica.edu.tw>