Remove default destructor definitions from cpp files (#5528)

code/Common/ScenePreprocessor.h

@@ -4,7 +4,6 @@ Open Asset Import Library (assimp)
 
 Copyright (c) 2006-2024, assimp team
 
-
 All rights reserved.
 
 Redistribution and use of this software in source and binary forms,
@@ -56,7 +55,7 @@ class ScenePreprocessorTest;
 namespace Assimp {
 
 // ----------------------------------------------------------------------------------
-/** ScenePreprocessor: Preprocess a scene before any post-processing
+/** ScenePreprocessor: Pre-process a scene before any post-processing
  *  steps are executed.
  *
  *  The step computes data that needn't necessarily be provided by the
@@ -79,6 +78,9 @@ public:
     ScenePreprocessor(aiScene *_scene) :
             scene(_scene) {}
 
+    /// @brief The class destructor.
+    ~ScenePreprocessor() = default;
+
     // ----------------------------------------------------------------
     /** Assign a (new) scene to the object.
      *