avutil/fifo: delay addition of const from 78d3453c4a until next major ABI bump

This unbreaks API, for example audacity has more build errors due to this

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavutil/fifo.c

@@ -59,12 +59,12 @@ void av_fifo_reset(AVFifoBuffer *f)
     f->wndx = f->rndx = 0;
 }
 
-int av_fifo_size(const AVFifoBuffer *f)
+int av_fifo_size(FF_CONST_AVUTIL53 AVFifoBuffer *f)
 {
     return (uint32_t)(f->wndx - f->rndx);
 }
 
-int av_fifo_space(const AVFifoBuffer *f)
+int av_fifo_space(FF_CONST_AVUTIL53 AVFifoBuffer *f)
 {
     return f->end - f->buffer - av_fifo_size(f);
 }

libavutil/fifo.h

@@ -65,7 +65,7 @@ void av_fifo_reset(AVFifoBuffer *f);
  * @param f AVFifoBuffer to read from
  * @return size
  */
-int av_fifo_size(const AVFifoBuffer *f);
+int av_fifo_size(FF_CONST_AVUTIL53 AVFifoBuffer *f);
 
 /**
  * Return the amount of space in bytes in the AVFifoBuffer, that is the
@@ -73,7 +73,7 @@ int av_fifo_size(const AVFifoBuffer *f);
  * @param f AVFifoBuffer to write into
  * @return size
  */
-int av_fifo_space(const AVFifoBuffer *f);
+int av_fifo_space(FF_CONST_AVUTIL53 AVFifoBuffer *f);
 
 /**
  * Feed data from an AVFifoBuffer to a user-supplied callback.