Add "check for updates" to main menu and AppMenu v2

Tag #963.

application/palemoon/base/content/baseMenuOverlay.xul

@@ -41,7 +41,7 @@
           label="&helpMenu.label;"
           accesskey="&helpMenu.accesskey;">
 #endif
-      <menupopup id="menu_HelpPopup">
+      <menupopup id="menu_HelpPopup" onpopupshowing="buildHelpMenu();">
         <menuitem id="menu_openHelp"
                   oncommand="openHelpLink('firefox-help')"
                   onclick="checkForMiddleClick(this, event);"
@@ -66,6 +66,14 @@
                   accesskey="&helpSafeMode.accesskey;"
                   label="&helpSafeMode.label;"
                   oncommand="restart(true);"/>
+        <menuseparator id="updateSeparator"/>
+        <menuitem id="checkForUpdates" class="menuitem-iconic"
+#ifdef MOZ_UPDATER
+                  label="&updateCmd.label;"
+                  oncommand="checkForUpdates();"/>
+#else
+                  hidden="true"/>
+#endif
         <menuseparator id="aboutSeparator"/>
         <menuitem id="aboutName"
                   accesskey="&aboutProduct.accesskey;"