Remove third_party libmkv.

source/libvpx/third_party/libmkv/EbmlWriter.h

Index: source/libvpx/third_party/libmkv/EbmlWriter.h
===================================================================
--- source/libvpx/third_party/libmkv/EbmlWriter.h	(revision 285926)
+++ source/libvpx/third_party/libmkv/EbmlWriter.h	(working copy)
@@ -1,42 +0,0 @@
-/*
- *  Copyright (c) 2010 The WebM project authors. All Rights Reserved.
- *
- *  Use of this source code is governed by a BSD-style license
- *  that can be found in the LICENSE file in the root of the source
- *  tree. An additional intellectual property rights grant can be found
- *  in the file PATENTS.  All contributing project authors may
- *  be found in the AUTHORS file in the root of the source tree.
- */
-#ifndef EBMLWRITER_HPP
-#define EBMLWRITER_HPP
-#include <stddef.h>
-#include "vpx/vpx_integer.h"
-
-/* note: you must define write and serialize functions as well as your own
- * EBML_GLOBAL
- *
- * These functions MUST be implemented
- */
-
-typedef struct EbmlGlobal EbmlGlobal;
-void  Ebml_Serialize(EbmlGlobal *glob, const void *, int, unsigned long);
-void  Ebml_Write(EbmlGlobal *glob, const void *, unsigned long);
-
-/*****/
-
-void Ebml_WriteLen(EbmlGlobal *glob, int64_t val);
-void Ebml_WriteString(EbmlGlobal *glob, const char *str);
-void Ebml_WriteUTF8(EbmlGlobal *glob, const wchar_t *wstr);
-void Ebml_WriteID(EbmlGlobal *glob, unsigned long class_id);
-void Ebml_SerializeUnsigned64(EbmlGlobal *glob, unsigned long class_id, uint64_t ui);
-void Ebml_SerializeUnsigned(EbmlGlobal *glob, unsigned long class_id, unsigned long ui);
-void Ebml_SerializeBinary(EbmlGlobal *glob, unsigned long class_id, unsigned long ui);
-void Ebml_SerializeFloat(EbmlGlobal *glob, unsigned long class_id, double d);
-/* TODO make this more generic to signed */
-void Ebml_WriteSigned16(EbmlGlobal *glob, short val);
-void Ebml_SerializeString(EbmlGlobal *glob, unsigned long class_id, const char *s);
-void Ebml_SerializeUTF8(EbmlGlobal *glob, unsigned long class_id, wchar_t *s);
-void Ebml_SerializeData(EbmlGlobal *glob, unsigned long class_id, unsigned char *data, unsigned long data_length);
-void Ebml_WriteVoid(EbmlGlobal *glob, unsigned long vSize);
-/* TODO need date function */
-#endif