Re: [PATCH 2/3] http: prefer CURLOPT_SEEKFUNCTION to CURLOPT_IOCTLFUNCTION

Jeff King [off-list ref] writes:

The IOCTLFUNCTION option has been deprecated, and generates a compiler
warning in recent versions of curl. We can switch to using SEEKFUNCTION
instead. It was added in 2008 via curl 7.18.0; our INSTALL file already
indicates we require at least curl 7.19.4.
...
+	if (offset < 0 || offset >= buffer->buf.len) {
+		error("curl seek would be outside of buffer");
+		return CURL_SEEKFUNC_FAIL;
 	}
+
+	buffer->posn = offset;
+	return CURL_SEEKFUNC_OK;
 }

Now we depend on having at least cURL 7.19.5 because
CURL_SEEKFUNC_{FAIL,OK} are not available before that version.

cf.  https://github.com/curl/curl/blob/master/docs/libcurl/symbols-in-versions#L127

Which is fine, as 7.19.5 is from May 2009 that is old enough.  We
just need to update the place where you got the 7.19.4 above from.

Thanks.