welcomeview: fix bad initialization

Tuleap: #1819
Change-Id: I2efb5d758beea6505dbc3ce5fd9b6da7b7109374
Reviewed-by: Olivier Soldano <olivier.soldano@savoirfairelinux.com>

src/ringwelcomeview.cpp

@@ -99,7 +99,7 @@ ring_welcome_update_view(RingWelcomeView* self, AccountContainer* accountContain
                                           priv->accountContainer_->info.profileInfo.uri.c_str());
     } else {
         gtk_label_set_text(GTK_LABEL(priv->label_explanation), NULL);
-        ring_id[0] = '\0';
+        ring_id = {};
     }
 
     gtk_label_set_markup(GTK_LABEL(priv->label_ringid), ring_id);