asfdemux: Add sanity check for asf_stream_audio
asfdemux: Add sanity check for asf_stream_audio

We should have enough bytes for the specified codec_data

https://bugzilla.gnome.org/show_bug.cgi?id=775070

GStreamer/gst-plugins-ugly,GrokImageCompression/gst-plugins-ugly,GStreamer/gst-plugins-ugly,GrokImageCompression/gst-plugins-ugly,GrokImageCompression/gst-plugins-ugly,StreamUtils/gst-plugins-ugly,StreamUtils/gst-plugins-ugly,StreamUtils/gst-plugins-ugly,GStreamer/gst-plugins-ugly