Cleanup properly at the end of MPEG Audio parsing.

Patch by Art Clarke (aclarke AT xuggle com)

Originally committed as revision 19327 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/mpegaudio_parser.c

@@ -145,5 +145,5 @@ AVCodecParser mpegaudio_parser = {
     sizeof(MpegAudioParseContext),
     NULL,
     mpegaudio_parse,
-    NULL,
+    ff_parse_close,
 };