bug#23128: 25.0.92; pcvs calls format-time-string with timezone 'utc.

[Eli Zaretskii]

> From: peder@klingenberg.no (Peder O. Klingenberg)
> Date: Sun, 27 Mar 2016 23:44:41 +0200
> 
> 
> >From 'emacs -Q':
> 
> (require 'pcvs)
> (cvs-fileinfo-from-entries "/some/cvscontrolled/file.txt")
> 
> Gives the backtrace:
> 
> Debugger entered--Lisp error: (error "Invalid time zone specification" utc)
>   format-time-string("%c" (22264 16191 0 0) utc)

Thanks, fixed.

(I still get an error after the fix, but the error is a different one,
so I presume it's unrelated.)