Trade: cleanup the dummy classes a bit.

They need to be at least movable to be returnable inside `std::optional`.

src/Trade/CameraData.h

@@ -35,12 +35,7 @@ namespace Magnum { namespace Trade {
 /**
 @brief %Camera data
 */
-class MAGNUM_EXPORT CameraData {
+class MAGNUM_EXPORT CameraData {};
-    CameraData(const CameraData&) = delete;
-    CameraData(CameraData&&) = delete;
-    CameraData& operator=(const CameraData&) = delete;
-    CameraData& operator=(CameraData&&) = delete;
-};
 
 }}
 

src/Trade/LightData.h

@@ -35,12 +35,7 @@ namespace Magnum { namespace Trade {
 /**
 @brief %Light data
 */
-class MAGNUM_EXPORT LightData {
+class MAGNUM_EXPORT LightData {};
-    LightData(const LightData&) = delete;
-    LightData(LightData&&) = delete;
-    LightData& operator=(const LightData&) = delete;
-    LightData& operator=(LightData&&) = delete;
-};
 
 }}