Add Assimp library in thirdparty

From https://github.com/assimp/assimp repo at d2b45377e4b09a1f43be95e45553afcc06b03f4b

thirdparty/assimp/code/CInterfaceIOWrapper.h

@@ -0,0 +1,99 @@
+/*
+---------------------------------------------------------------------------
+Open Asset Import Library (assimp)
+---------------------------------------------------------------------------
+
+Copyright (c) 2006-2019, assimp team
+
+
+
+All rights reserved.
+
+Redistribution and use of this software in source and binary forms,
+with or without modification, are permitted provided that the following
+conditions are met:
+
+* Redistributions of source code must retain the above
+  copyright notice, this list of conditions and the
+  following disclaimer.
+
+* Redistributions in binary form must reproduce the above
+  copyright notice, this list of conditions and the
+  following disclaimer in the documentation and/or other
+  materials provided with the distribution.
+
+* Neither the name of the assimp team, nor the names of its
+  contributors may be used to endorse or promote products
+  derived from this software without specific prior
+  written permission of the assimp team.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+---------------------------------------------------------------------------
+*/
+
+/** @file aiFileIO -> IOSystem wrapper*/
+
+#ifndef AI_CIOSYSTEM_H_INCLUDED
+#define AI_CIOSYSTEM_H_INCLUDED
+
+#include <assimp/cfileio.h>
+#include <assimp/IOStream.hpp>
+#include <assimp/IOSystem.hpp>
+
+namespace Assimp    {
+
+class CIOSystemWrapper;
+
+// ------------------------------------------------------------------------------------------------
+// Custom IOStream implementation for the C-API
+class CIOStreamWrapper : public IOStream
+{
+public:
+    explicit CIOStreamWrapper(aiFile* pFile, CIOSystemWrapper* io)
+        : mFile(pFile),
+        mIO(io)
+    {}
+    ~CIOStreamWrapper(void);
+
+    size_t Read(void* pvBuffer, size_t pSize, size_t pCount);
+    size_t Write(const void* pvBuffer, size_t pSize, size_t pCount);
+    aiReturn Seek(size_t pOffset, aiOrigin pOrigin);
+    size_t Tell(void) const;
+    size_t FileSize() const;
+    void Flush();
+
+private:
+    aiFile* mFile;
+    CIOSystemWrapper* mIO;
+};
+
+class CIOSystemWrapper : public IOSystem
+{
+    friend class CIOStreamWrapper;
+public:
+    explicit CIOSystemWrapper(aiFileIO* pFile)
+        : mFileSystem(pFile)
+    {}
+
+    bool Exists( const char* pFile) const;
+    char getOsSeparator() const;
+    IOStream* Open(const char* pFile,const char* pMode = "rb");
+    void Close( IOStream* pFile);
+private:
+    aiFileIO* mFileSystem;
+};
+
+}
+
+#endif
+