casync-http: set curl verbosity

Enable CURL verbosity for the notice and higher log levels (ie. debug).

When CURLOPT_VERBOSE is enabled, libcurl outputs traces to stderr, such
as headers and a lot of internal information.

Now, the libcurl verbose informations are dumped to stdout when the
options --log-level notice or debug are specified to casync.

Author: gportay

src/casync-http.c

@@ -205,7 +205,7 @@ static int make_curl_easy_handle(CURL **ret,
         if (arg_ssl_trust_peer)
                 CURL_SETOPT_EASY(h, CURLOPT_SSL_VERIFYPEER, false);
 
-        /* CURL_SETOPT_EASY(h, CURLOPT_VERBOSE, 1L); */
+        CURL_SETOPT_EASY(h, CURLOPT_VERBOSE, arg_log_level > 4);
 
         *ret = TAKE_PTR(h);
         return 0;