used in loops, rewrite to range based loop

oox/source/drawingml/color.cxx has some mappings in plain arrays
make them arrays of pairs which can be used in range based loops

Change-Id: Ib6693197d890f595c27ca24b9f9b4e0763747f4c
Reviewed-on: https://gerrit.libreoffice.org/24809Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Jochen Nitschke <j.nitschke+logerrit@ok.de>