Trade: ensure the deprecated SceneData constructor uses default deleters.

Otherwise the instances wouldn't be usable from AbstractImporter
subclasses.

src/Magnum/Trade/SceneData.cpp

@@ -749,9 +749,11 @@ SceneData::SceneData(std::vector<UnsignedInt> children2D, std::vector<UnsignedIn
         {NoInit, children.size(), objects},
         {NoInit, children.size(), parents},
     };
-    _fields = {InPlaceInit, {
+    /* Can't use InPlaceInit as that creates an Array with a non-default
-        SceneFieldData{SceneField::Parent, objects, parents}
+       deleter, which then trips up on an assertion when such an instance gets
-    }};
+       returned from AbstractImporter */
+    _fields = Containers::Array<SceneFieldData>{1};
+    _fields[0] = SceneFieldData{SceneField::Parent, objects, parents};
     Utility::copy(children, objects);
     constexpr Int parent[]{-1};
     Utility::copy(Containers::stridedArrayView(parent).broadcasted<0>(parents.size()), parents);

src/Magnum/Trade/Test/SceneDataTest.cpp

@@ -1508,6 +1508,11 @@ void SceneDataTest::constructDeprecated() {
        is set directly */
     CORRADE_COMPARE(scene.is2D(), data.is2D);
     CORRADE_COMPARE(scene.is3D(), data.is3D);
+
+    /* The deleters have to be trivial, otherwise this instance wouldn't be
+       usable from an AbstractImporter */
+    CORRADE_VERIFY(!scene.releaseFieldData().deleter());
+    CORRADE_VERIFY(!scene.releaseData().deleter());
 }
 
 void SceneDataTest::constructDeprecatedBoth2DAnd3D() {