This wasn't a problem before, as EnhancedCustomShapeTypeNames wasn't
involved for the export of rectangles, as those were handled in sw
directly.

CppunitTest_sw_ooxmlsdrexport's testFdo69636 is a reproducer for this
problem, the VML fallback part was empty due to this.

Change-Id: Ib2622fe05ddaa66bb3231977e30a8a1ca8748001