SdrObjList::Clear() does broadcast the SdrObject
removals and deletions and a SetChanged() to SdrModel.
The old version avoided this in the destructor (with
a comment to not call virtual methods in destructor,
but  the problem is more that the ::Notify triggered
works on the SdrPage already in destruction). To allow
calls to Clear() without broadcasting I splitted this
to a impClearSdrObjList(bool bBrodacast) and rename
of ::Clear to ::ClearSdrObjList to get all places.
Adapted all places in the code as needed, already pre-
checked on Linux that this fixes the problem.

Change-Id: Iea46758fb6b57f2b3d9896959a35260c6f6d52d5
Reviewed-on: https://gerrit.libreoffice.org/53839Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Armin Le Grand <Armin.Le.Grand@cib.de>