Update public FFmpeg header files from r16647 to r18286.

third_party/ffmpeg/include/libavutil/crc.h

 /*
  * copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at>
  *
  * This file is part of FFmpeg.
  *
  * FFmpeg is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2.1 of the License, or (at your option) any later version.
  *
@@ skipping 15 matching lines @@
 #include "common.h"
 
 typedef uint32_t AVCRC;
 
 typedef enum {
     AV_CRC_8_ATM,
     AV_CRC_16_ANSI,
     AV_CRC_16_CCITT,
     AV_CRC_32_IEEE,
     AV_CRC_32_IEEE_LE,  /*< reversed bitorder version of AV_CRC_32_IEEE */
-    AV_CRC_MAX,         /*< not part of public API! don't use outside lavu */
+    AV_CRC_MAX,         /*< Not part of public API! Do not use outside libavutil. */
 }AVCRCId;
 
 int av_crc_init(AVCRC *ctx, int le, int bits, uint32_t poly, int ctx_size);
 const AVCRC *av_crc_get_table(AVCRCId crc_id);
 uint32_t av_crc(const AVCRC *ctx, uint32_t start_crc, const uint8_t *buffer, size_t length) av_pure;
 
 #endif /* AVUTIL_CRC_H */