Obj: remove smooth-normals postprocessing (#6031)

- closes https://github.com/assimp/assimp/issues/5514

code/Common/Exporter.cpp

@@ -3,7 +3,7 @@
 Open Asset Import Library (assimp)
 ---------------------------------------------------------------------------
 
-Copyright (c) 2006-2024, assimp team
+Copyright (c) 2006-2025, assimp team
 
 All rights reserved.
 
@@ -159,10 +159,8 @@ static void setupExporterArray(std::vector<Exporter::ExportFormatEntry> &exporte
 #endif
 
 #ifndef ASSIMP_BUILD_NO_OBJ_EXPORTER
-	exporters.emplace_back("obj", "Wavefront OBJ format", "obj", &ExportSceneObj,
-			aiProcess_GenSmoothNormals /*| aiProcess_PreTransformVertices */);
-	exporters.emplace_back("objnomtl", "Wavefront OBJ format without material file", "obj", &ExportSceneObjNoMtl,
-			aiProcess_GenSmoothNormals /*| aiProcess_PreTransformVertices */);
+	exporters.emplace_back("obj", "Wavefront OBJ format", "obj", &ExportSceneObj);
+	exporters.emplace_back("objnomtl", "Wavefront OBJ format without material file", "obj", &ExportSceneObjNoMtl);
 #endif
 
 #ifndef ASSIMP_BUILD_NO_STL_EXPORTER