by using for-range loops
+ remove useless vars
+ avoid some iterators calculus by using plain loop

Change-Id: I94572bfd56ad9ac76c9899cf68d5ba831009fa7b
Reviewed-on: https://gerrit.libreoffice.org/48777Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Julien Nabet <serval2412@yahoo.fr>