daemon: don't use deprecated avcodec_alloc_frame

avcodec_alloc_frame is an deprecated API.
Now use av_frame_alloc.
libav_deps.h take care of backward compatibility.

Change-Id: Ifaf27e6908d09b5772c04fb819243901a3cb5660

daemon/src/media/media_encoder.cpp

@@ -346,7 +346,7 @@ int MediaEncoder::encode_audio(const AudioBuffer &buffer)
     const auto sample_rate = buffer.getSampleRate();
 
     while (nb_frames > 0) {
-        AVFrame *frame = avcodec_alloc_frame();
+        AVFrame *frame = av_frame_alloc();
         if (!frame) {
             av_freep(&sample_data);
             return -1;