libraries: add assimp

<https://github.com/assimp/assimp>

.gitmodules

@@ -246,3 +246,6 @@
 [submodule "libraries/libarchive"]
 	path = libraries/libarchive
 	url = https://github.com/libarchive/libarchive
+[submodule "libraries/assimp"]
+	path = libraries/assimp
+	url = https://github.com/assimp/assimp

config.py

@@ -45,6 +45,58 @@ def sparse_paths(self):
         "av1/common/blockd.h",
         "av1/decoder/decodemv.c",
         ]),
+    Library('assimp', [
+        "code/AssetLib/FBX/FBXConverter.cpp",
+        "code/AssetLib/glTF2/glTF2Importer.cpp",
+        "code/AssetLib/Collada/ColladaParser.cpp",
+        "code/AssetLib/Collada/ColladaLoader.cpp",
+        "code/AssetLib/Obj/ObjFileParser.cpp",
+        "code/Common/Importer.cpp",
+        "code/AssetLib/glTF2/glTF2Exporter.cpp",
+        "code/AssetLib/Obj/ObjFileImporter.cpp",
+        "code/Common/Exporter.cpp",
+        "code/AssetLib/glTF2/glTF2Asset.h",
+        "code/Common/BaseImporter.cpp",
+        "code/AssetLib/FBX/FBXDocument.cpp",
+        "code/AssetLib/Collada/ColladaExporter.cpp",
+        "code/AssetLib/LWO/LWOLoader.cpp",
+        "code/AssetLib/Blender/BlenderLoader.cpp",
+        "code/AssetLib/3DS/3DSLoader.cpp",
+        "include/assimp/material.h",
+        "code/AssetLib/MDL/MDLLoader.cpp",
+        "include/assimp/mesh.h",
+        "code/AssetLib/STL/STLLoader.cpp",
+        "code/AssetLib/ASE/ASEParser.cpp",
+        "code/AssetLib/FBX/FBXMeshGeometry.cpp",
+        "code/AssetLib/ASE/ASELoader.cpp",
+        "code/PostProcessing/ValidateDataStructure.cpp",
+        "code/AssetLib/IFC/IFCOpenings.cpp",
+        "code/AssetLib/IFC/IFCGeometry.cpp",
+        "code/AssetLib/FBX/FBXParser.cpp",
+        "code/AssetLib/IFC/IFCLoader.cpp",
+        "code/AssetLib/OpenGEX/OpenGEXImporter.cpp",
+        "include/assimp/BaseImporter.h",
+        "include/assimp/types.h",
+        "code/AssetLib/SMD/SMDLoader.cpp",
+        "code/AssetLib/DXF/DXFLoader.cpp",
+        "code/AssetLib/Obj/ObjFileMtlImporter.cpp",
+        "include/assimp/defs.h",
+        "code/AssetLib/Irr/IRRLoader.cpp",
+        "include/assimp/Importer.hpp",
+        "code/Common/SceneCombiner.cpp",
+        "code/AssetLib/Ply/PlyLoader.cpp",
+        "code/AssetLib/FBX/FBXExporter.cpp",
+        "test/unit/utglTF2ImportExport.cpp",
+        "code/AssetLib/FBX/FBXDocument.h",
+        "code/AssetLib/X/XFileImporter.cpp",
+        "code/AssetLib/3DS/3DSConverter.cpp",
+        "code/AssetLib/MD3/MD3Loader.cpp",
+        "code/AssetLib/glTF/glTFImporter.cpp",
+        "code/AssetLib/3DS/3DSHelper.h",
+        "code/Common/Assimp.cpp",
+        "code/AssetLib/glTF/glTFExporter.cpp",
+        "code/AssetLib/X/XFileParser.cpp",
+        ]),
     Library('boringssl', [
         "ssl/internal.h",
         "ssl/ssl_lib.cc",
@@ -1046,6 +1098,10 @@ def sparse_paths(self):
 # Some libraries embed code themselves:
 embedded = {
     "aom":        ["googletest"],
+    # assimp: some of these embeddings are just incidental duplicates,
+    # like CMake scripts or Markdown templates.
+    "assimp":     ["aom", "googletest", "zlib", "minizip-ng", "boringssl",
+                   "mbedtls"],
     "boringssl":  ["googletest"],
     # botan embeds numerous test files from these:
     "botan":      ["boringssl", "mbedtls"],