Otherwise the gradient won't be commited to the Metafile, as
mbOutputClipped will be true, because the output device will
have just one pixel size.

Change-Id: I73084eb715ee6313f6478eded24feb9abfc411f3
Reviewed-on: https://gerrit.libreoffice.org/73423
Tested-by: Jenkins
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>