bnc#885825: OOXML import and export of data label borders.

(cherry picked from commit 48f31a924280a418046f0c816f8a7d20b672dac6)

Conflicts:
	oox/source/export/chartexport.cxx

Change-Id: I0fd808145aaeb0aa36d3ec30d7b977890642dcff
Reviewed-on: https://gerrit.libreoffice.org/10562
Reviewed-by: Markus Mohrhard <markus.mohrhard@googlemail.com>
Tested-by: Markus Mohrhard <markus.mohrhard@googlemail.com>