retry: consider retrying even if -f is used

The --retry logic does retry HTTP when some specific response codes are
returned, but because the -f option sets the CURLOPT_FAILONERROR to
libcurl, the return codes are different for such situations and then the
curl tool failed to consider it for retrying.

Reported by: Mike Power
Bug: http://curl.haxx.se/bug/view.cgi?id=3037362