ole32: If number of VT_VECTOR elements is 0 there is no need to allocate memory.

dlls/ole32/ole2.c

@@ -3143,7 +3143,7 @@ HRESULT WINAPI PropVariantCopy(PROPVARIANT *pvarDest,      /* [out] */
                 return E_INVALIDARG;
             }
             len = pvarSrc->u.capropvar.cElems;
-            pvarDest->u.capropvar.pElems = CoTaskMemAlloc(len * elemSize);
+            pvarDest->u.capropvar.pElems = len ? CoTaskMemAlloc(len * elemSize) : NULL;
             if (pvarSrc->vt == (VT_VECTOR | VT_VARIANT))
             {
                 for (i = 0; i < len; i++)

dlls/ole32/tests/propvariant.c

@@ -263,7 +263,6 @@ static void test_validtypes(void)
         {
             ok(copy.vt == propvar.vt, "expected %d, got %d\n", propvar.vt, copy.vt);
             ok(!U(copy).caub.cElems, "%u: expected 0, got %d\n", i, U(copy).caub.cElems);
-todo_wine
             ok(!U(copy).caub.pElems, "%u: expected NULL, got %p\n", i, U(copy).caub.pElems);
         }
         else