Update git submodules

* Update helpcontent2 from branch 'master'
  - Prepare to handle native SVG icons
    
    Today icons are PNG images, if later they become SVG natively...
    
    Change-Id: I42d886257b55b5676767c8b8879a6bf35eb4d5e6
    Reviewed-on: https://gerrit.libreoffice.org/60156
    Tested-by: Jenkins
Reviewed-by: Olivier Hallot <olivier.hallot@libreoffice.org>
    

helpcontent2 @ f3124329

-Subproject commit caa4981835ffce40ba409f05435a5ecc08be80b6
+Subproject commit f3124329e336603ba6684e913a61a58e7a202020