The date format in RFC822 allows that the seconds part of HH:MM:SS is
left out, but this function didn't allow it. This change also includes a
modified test case that makes sure that this now works.
Reported by: Matt Ford
Bug: http://curl.haxx.se/bug/view.cgi?id=3076529
mail posted to the http-state mailing list, from Adam Barth, and is said to be
the set of date formats the Chrome browser code is tested against:
http://www.ietf.org/mail-archive/web/http-state/current/msg00129.html
libcurl parses most of them identically, but not all of them.