AudioConverter: register as boxed type

https://bugzilla.gnome.org/show_bug.cgi?id=793492

docs/libs/gst-plugins-base-libs-sections.txt

@@ -670,6 +670,7 @@ gst_audio_converter_reset
 gst_audio_converter_supports_inplace
 <SUBSECTION Standard>
 gst_audio_converter_flags_get_type
+gst_audio_converter_get_type
 </SECTION>
 
 <SECTION>

gst-libs/gst/audio/audio-converter.c

@@ -141,6 +141,20 @@ struct _GstAudioConverter
   AudioConvertSamplesFunc convert;
 };
 
+static GstAudioConverter *
+gst_audio_converter_copy (GstAudioConverter * convert)
+{
+  GstAudioConverter *res =
+      gst_audio_converter_new (convert->flags, &convert->in, &convert->out,
+      convert->config);
+
+  return res;
+}
+
+G_DEFINE_BOXED_TYPE (GstAudioConverter, gst_audio_converter,
+    (GBoxedCopyFunc) gst_audio_converter_copy,
+    (GBoxedFreeFunc) gst_audio_converter_free);
+
 typedef gboolean (*AudioChainFunc) (AudioChain * chain, gpointer user_data);
 typedef gpointer *(*AudioChainAllocFunc) (AudioChain * chain, gsize num_samples,
     gpointer user_data);

gst-libs/gst/audio/audio-converter.h

@@ -121,6 +121,9 @@ GstAudioConverter *  gst_audio_converter_new             (GstAudioConverterFlags
                                                           GstAudioInfo *out_info,
                                                           GstStructure *config);
 
+GST_EXPORT
+GType                gst_audio_converter_get_type        (void);
+
 GST_EXPORT
 void                 gst_audio_converter_free            (GstAudioConverter * convert);