With previous implementation of closing shapes, we are adding
new line between last and first point.
It was causing wrong border shape during displaying.
With this patch proper method was used to fix that.

Change-Id: If0a084700401edd9d3b8a57cb27154079828e6ed
Reviewed-on: https://gerrit.libreoffice.org/52843Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Patrick Jaap <patrick.jaap@tu-dresden.de>
Reviewed-by: Bartosz Kosiorek <gang65@poczta.onet.pl>