Log Message:
mate-icon-theme: update to 1.21.1:

### mate-icon-theme 1.21.1

  * Translations update
  * Add video single and joined display symbolic svg icons
  * symlink input-touchpad.svg icon
  * add a symlink for bluetooth icon
  * add icons for touchpad

### mate-icon-theme 1.21.0

  * Translations update
  * mate: add audio-volume-off