decoder/ffmpeg: free URI, fix memory leak

Free the string allocated by decoder_get_uri().

NEWS

@@ -5,6 +5,7 @@ ver 0.15.11 (2010/??/??)
   - mp4ff: support tags "album artist", "albumartist", "band"
   - mikmod: fix memory leak
   - vorbis: handle uri==NULL
+  - ffmpeg: fix memory leak
   - ffmpeg: free AVFormatContext on error
   - ffmpeg: read more metadata
 * playlist: emit IDLE_OPTIONS when resetting single mode

src/decoder/ffmpeg_plugin.c

@@ -376,8 +376,10 @@ ffmpeg_decode(struct decoder *decoder, struct input_stream *input)
 	ctx.input = input;
 	ctx.decoder = decoder;
 
-	ffmpeg_helper(decoder_get_uri(decoder), input,
+	char *uri = decoder_get_uri(decoder);
+	ffmpeg_helper(uri, input,
 		      ffmpeg_decode_internal, &ctx);
+	g_free(uri);
 }
 
 #if LIBAVFORMAT_VERSION_INT >= ((52<<16)+(31<<8)+0)