...so that the dynamic_cast also works on macOS (where RTTI equivalence is
determined by address, not by strcmp).  The two relevant dynamic_casts are in
BezierObjectBar::GetAttrState and BezierObjectBar::Execute (both in
sd/source/ui/view/drbezob.cxx).  (They can be triggered from the Impress UI by
adding any "Motion Paths" animation to a shape, then selecting and manipulating
the path's control points.)

The source of those dynamic_casts appears to always be sd::MotionPathTag,
defined in sd/source/ui/animations/motionpathtag.hxx in the same library, so
wouldn't technically require IPolyPolygonEditorController to be
SAL_DLLPUBLIC_RTTI.  However, while 367e8743
"INTEGRATION: CWS pathfinder01" introduced that sd::MotionPathTag deriving from
IPolyPolygonEditorController, 346e0ffe
"INTEGRATION: CWS pathfinder01: #i41800# added inteface
IPolyPolygonEditorControler to allow edit of non marked path objects" also added
IPolyPolygonEditorController to SdrPolyEditView in include/svx/svdpoev.hxx, for
unclear reasons.  So better be conservative and assume SAL_DLLPUBLIC_RTTI is
needed after all.

Change-Id: Ieefabf7b00357876046014bbff098076108f9dea
Reviewed-on: https://gerrit.libreoffice.org/50109Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>