avcodec/vp3: Fix several memleaks

Fixes: 1536b9b096a8f95b742bae9d3d761cc6/signal_sigsegv_294aaed_4460_b209bd1e7cebe458b53072a44191316d.ogg

Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavcodec/vp3.c

@@ -2025,6 +2025,7 @@ static int vp3_decode_frame(AVCodecContext *avctx,
             }
             return ret;
         } else if (type == 2) {
+            vp3_decode_end(avctx);
             ret = theora_decode_tables(avctx, &gb);
             if (ret >= 0)
                 ret = vp3_decode_init(avctx);