debian-changelog-mode support for non-coreutils systems

Status changed to 'Confirmed' because the bug affects multiple users.

I marked this as "affects me too", not because it particularly affects me, but because it is clearly a code improvement -- provided the locale-specific format-time-string parameters are substituted with locale-independent constructs (in particular, %b expands to the locale's abbreviated month name; I don't know if there is a way to override the locale locally [sic] or if you would have to hard-code, say, a vector of English month names).

Good catch. Fixed through https://github.com/pcarrier/debian-changelog-mode/commit/285d4cc938468fd3d7d74584da7981705727fbab

For reference:

(let ((system-time-locale "fr_FR"))
  (format-time-string "%a, %d %b %Y %T %z" nil
                      debian-changelog-date-utc-flag))
"Ven, 05 jul 2013 17:51:39 +0200"

(let ((system-time-locale "C"))
  (format-time-string "%a, %d %b %Y %T %z" nil
                      debian-changelog-date-utc-flag))
"Fri, 05 Jul 2013 17:51:53 +0200"