MDL-71741 portfolio: Reset header information between requests

The reset process also removes the CURLFile option in the HTTP object,
which will avoid the serialisation issue on PHP7.4 and upward

lib/flickrclient.php

@@ -235,6 +235,9 @@ class flickr_client extends oauth_helper {
 
         $response = $this->http->post(self::UPLOAD_ROOT, $params);
 
+        // Reset http header and options to prepare for the next request.
+        $this->reset_state();
+
         if ($response) {
             $xml = simplexml_load_string($response);
 
@@ -254,4 +257,14 @@ class flickr_client extends oauth_helper {
             throw new moodle_exception('flickr_upload_error', 'core_error', '', null, $response);
         }
     }
+
+    /**
+     * Resets curl state.
+     *
+     * @return void
+     */
+    public function reset_state(): void {
+        $this->http->cleanopt();
+        $this->http->resetHeader();
+    }
 }