New FFmpeg public API headers to match our source tarball in deps.

third_party/ffmpeg/include/libavutil/fifo.h

 /*
  * 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.
  *
  * FFmpeg is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 44 matching lines @@
 
 /**
  * Returns the amount of data in bytes in the AVFifoBuffer, that is the
  * amount of data you can read from it.
  * @param *f AVFifoBuffer to read from
  * @return size
  */
 int av_fifo_size(AVFifoBuffer *f);
 
 /**
+ * Returns the amount of space in bytes in the AVFifoBuffer, that is the
+ * amount of data you can write into it.
+ * @param *f AVFifoBuffer to write into
+ * @return size
+ */
+int av_fifo_space(AVFifoBuffer *f);
+
+/**
  * Feeds data from an AVFifoBuffer to a user-supplied callback.
  * @param *f AVFifoBuffer to read from
  * @param buf_size number of bytes to read
  * @param *func generic read function
  * @param *dest data destination
  */
 int av_fifo_generic_read(AVFifoBuffer *f, void *dest, int buf_size, void (*func)(void*, void*, int));
 
 /**
  * Feeds data from a user-supplied callback to an AVFifoBuffer.
@@ skipping 25 matching lines @@
 void av_fifo_drain(AVFifoBuffer *f, int size);
 
 static inline uint8_t av_fifo_peek(AVFifoBuffer *f, int offs)
 {
     uint8_t *ptr = f->rptr + offs;
     if (ptr >= f->end)
         ptr -= f->end - f->buffer;
     return *ptr;
 }
 #endif /* AVUTIL_FIFO_H */