avcodec/tiff: Clear deinvert_buf_size on deallocation

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavcodec/tiff.c

@@ -1411,6 +1411,7 @@ static av_cold int tiff_end(AVCodecContext *avctx)
 
     ff_lzw_decode_close(&s->lzw);
     av_freep(&s->deinvert_buf);
+    s->deinvert_buf_size = 0;
     av_freep(&s->fax_buffer);
     s->fax_buffer_size = 0;
     return 0;