appmenus: defer menu cache regeneration to speedup qvm-sync-appmenus

Call "xdg-desktop-menu forceupdate" at the end of the process, not for
every single item.

appmenus-scripts/create-apps-for-appvm.sh

@@ -56,8 +56,9 @@ if [ "$SRCDIR" != "none" ]; then
 fi
 
 echo "--> Adding Apps to the Menu..."
-LC_COLLATE=C xdg-desktop-menu install $APPSDIR/*.directory $APPSDIR/*.desktop
+LC_COLLATE=C xdg-desktop-menu install --noupdate $APPSDIR/*.directory $APPSDIR/*.desktop
 
 if [ -n "$KDE_SESSION_UID" -a -z "$SKIP_CACHE_REBUILD" ]; then
+    xdg-desktop-menu forceupdate
     kbuildsycoca4
 fi

appmenus-scripts/qubes-receive-appmenus

@@ -366,6 +366,7 @@ def main():
             except Exception, e:
                 print >> sys.stderr, "---> Failed to recreate appmenus for " \
                                      "'{0}': {1}".format(child_vm.name, str(e))
+        subprocess.call(['xdg-desktop-menu', 'forceupdate'])
         if 'KDE_SESSION_UID' in os.environ:
             subprocess.call(['kbuildsycoca4'])
         os.unsetenv('SKIP_CACHE_REBUILD')