Revert "assimp: Sync with upstream 0201fc5"

This reverts commit 78b22393a8.

It caused a regression in FBX import leading to crashes.
Fixes #36908.

(cherry picked from commit da1f80c1f2)

thirdparty/assimp/code/PostProcessing/ProcessHelper.cpp

@@ -2,7 +2,7 @@
 Open Asset Import Library (assimp)
 ----------------------------------------------------------------------
 
-Copyright (c) 2006-2020, assimp team
+Copyright (c) 2006-2019, assimp team
 
 
 All rights reserved.
@@ -230,6 +230,46 @@ VertexWeightTable* ComputeVertexBoneWeightTable(const aiMesh* pMesh)
     return avPerVertexWeights;
 }
 
+
+// -------------------------------------------------------------------------------
+const char* TextureTypeToString(aiTextureType in)
+{
+    switch (in)
+    {
+    case aiTextureType_NONE:
+        return "n/a";
+    case aiTextureType_DIFFUSE:
+        return "Diffuse";
+    case aiTextureType_SPECULAR:
+        return "Specular";
+    case aiTextureType_AMBIENT:
+        return "Ambient";
+    case aiTextureType_EMISSIVE:
+        return "Emissive";
+    case aiTextureType_OPACITY:
+        return "Opacity";
+    case aiTextureType_NORMALS:
+        return "Normals";
+    case aiTextureType_HEIGHT:
+        return "Height";
+    case aiTextureType_SHININESS:
+        return "Shininess";
+    case aiTextureType_DISPLACEMENT:
+        return "Displacement";
+    case aiTextureType_LIGHTMAP:
+        return "Lightmap";
+    case aiTextureType_REFLECTION:
+        return "Reflection";
+    case aiTextureType_UNKNOWN:
+        return "Unknown";
+    default:
+        break;
+    }
+
+    ai_assert(false);
+    return  "BUG";
+}
+
 // -------------------------------------------------------------------------------
 const char* MappingTypeToString(aiTextureMapping in)
 {