Replace simple while loops with range-based for-loops when apropriate.
There should be no side effects due to this change.

Change-Id: I0c39d4c10c991354248e864a09333144974c953c
Reviewed-on: https://gerrit.libreoffice.org/19281Reviewed-by: Noel Grandin <noelgrandin@gmail.com>
Tested-by: Noel Grandin <noelgrandin@gmail.com>