avutil: add av_buffer_get_ref_count()

This function is quite usefull for debuging
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavutil/buffer.c

@@ -130,6 +130,11 @@ void *av_buffer_get_opaque(const AVBufferRef *buf)
     return buf->buffer->opaque;
 }
 
+int av_buffer_get_ref_count(const AVBufferRef *buf)
+{
+    return buf->buffer->refcount;
+}
+
 int av_buffer_make_writable(AVBufferRef **pbuf)
 {
     AVBufferRef *newbuf, *buf = *pbuf;

libavutil/buffer.h

@@ -167,6 +167,8 @@ int av_buffer_is_writable(const AVBufferRef *buf);
  */
 void *av_buffer_get_opaque(const AVBufferRef *buf);
 
+int av_buffer_get_ref_count(const AVBufferRef *buf);
+
 /**
  * Create a writable reference from a given buffer reference, avoiding data copy
  * if possible.