EMF+: Fill line cap object if EmfPlusCustomLineCapDataFillPath is set.

Change-Id: I7b53a8f18e1fb24b1ae0322bdf0980e431a0725f
(cherry picked from commit 131f3230d98f24faf57d9404e333cb1fb183345b)
Reviewed-on: https://gerrit.libreoffice.org/6960
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>