tdf#135755: Crash:right click to Manage Changes List on side bar

bt here:
https://bugs.documentfoundation.org/attachment.cgi?id=164318&action=edit

Change-Id: I0874cf9bea1e28192e94ea6125ca6ac8f5736c30
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/100759
Tested-by: Jenkins
Reviewed-by: Julien Nabet <serval2412@yahoo.fr>

sw/uiconfig/swriter/ui/managechangessidebar.ui

@@ -166,7 +166,7 @@
         <property name="label" translatable="yes" context="managechangessidebar|writersort">Sort By</property>
         <property name="use_underline">True</property>
         <child type="submenu">
-          <object class="GtkMenu">
+          <object class="GtkMenu" id="writersortmenu">
             <property name="visible">True</property>
             <property name="can_focus">False</property>
             <child>