aacparse: fix codec_data buffer leak

https://bugzilla.gnome.org/show_bug.cgi?id=740101
diff --git a/gst/audioparsers/gstaacparse.c b/gst/audioparsers/gstaacparse.c
index 3c7c716..ad81a54 100644
--- a/gst/audioparsers/gstaacparse.c
+++ b/gst/audioparsers/gstaacparse.c
@@ -248,6 +248,7 @@
         gst_buffer_fill (codec_data_buffer, 0, codec_data, 2);
         gst_caps_set_simple (src_caps, "codec_data", GST_TYPE_BUFFER,
             codec_data_buffer, NULL);
+        gst_buffer_unref (codec_data_buffer);
       }
     } else if (aacparse->header_type == DSPAAC_HEADER_NONE) {
       GST_DEBUG_OBJECT (GST_BASE_PARSE (aacparse)->srcpad,