Merge r307360 from stable/9:

Merge r307360 from stable/9:

  Incorporate a change from OpenBSD by millert@OpenBSD.org

  Don't warn about valid time zone abbreviations.  POSIX
  through 2000 says that an abbreviation cannot start with ':', and
  cannot contain ',', '-', '+', NUL, or a digit.  POSIX from 2001
  on changes this rule to say that an abbreviation can contain only
  '-', '+', and alphanumeric characters from the portable character
  set in the current locale.  To be portable to both sets of rules,
  an abbreviation must therefore use only ASCII letters."  Adapted
  from tzcode2015f.

Errata Notice:	EN-16:19.tzcode
Approved by:	so

git-svn-id: svn://svn.freebsd.org/base/releng/9.3@309567 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f