avcodec/audioconvert: deprecate API

Note, the header was not installed so useage of this should be limited
but its not 0, there are some random pieces of code using it according
to google.

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

libavcodec/audioconvert.h

@@ -45,14 +45,20 @@ typedef struct AVAudioConvert AVAudioConvert;
  * @param[in] matrix Channel mixing matrix (of dimension in_channel*out_channels). Set to NULL to ignore.
  * @param flags See AV_CPU_FLAG_xx
  * @return NULL on error
+ * @deprecated See libswresample
  */
+
+attribute_deprecated
 AVAudioConvert *av_audio_convert_alloc(enum AVSampleFormat out_fmt, int out_channels,
                                        enum AVSampleFormat in_fmt, int in_channels,
                                        const float *matrix, int flags);
 
 /**
  * Free audio sample format converter context
+ * @deprecated See libswresample
  */
+
+attribute_deprecated
 void av_audio_convert_free(AVAudioConvert *ctx);
 
 /**
@@ -62,7 +68,10 @@ void av_audio_convert_free(AVAudioConvert *ctx);
  * @param[in] in array of input buffers for each channel
  * @param[in] in_stride distance between consecutive input samples (measured in bytes)
  * @param len length of audio frame size (measured in samples)
+ * @deprecated See libswresample
  */
+
+attribute_deprecated
 int av_audio_convert(AVAudioConvert *ctx,
                            void * const out[6], const int out_stride[6],
                      const void * const  in[6], const int  in_stride[6], int len);