ptx image decoder uses get_buffer, set CODEC_CAP_DR1

Originally committed as revision 19101 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/ptx.c

@@ -114,7 +114,7 @@ AVCodec ptx_decoder = {
     NULL,
     ptx_end,
     ptx_decode_frame,
-    0,
+    CODEC_CAP_DR1,
     NULL,
     .long_name = NULL_IF_CONFIG_SMALL("V.Flash PTX image"),
 };