ap_parseHTTPdate — convert an HTTP date to Unix time
time_t ap_parseHTTPdate(const char *date)
Parses a date in one of three formats, returning the time in seconds since 1 Jan 1970 00:00 GMT. The three formats are as follows:
Sun, 06 Nov 1994 08:49:37 GMT (RFC 822, updated by RFC 1123)
Sunday, 06-Nov-94 08:49:37 GMT (RFC 850, made obsolete by RFC 1036)
Sun Nov 6 08:49:37 1994 (ANSI C asctime() format)
Note that since HTTP requires dates to be in GMT, this routine ignores the time-zone field.