EMF+: Only draw endcap outline if not filled, fix endcap scaling.

Change-Id: I4520eea08e43ccd657c1db03b258ef84612da971
Reviewed-on: https://gerrit.libreoffice.org/7726
Reviewed-by: Jan Holesovsky <kendy@collabora.com>
Tested-by: Jan Holesovsky <kendy@collabora.com>