libavcodec/wmalosslessdec: Check the remaining bits

Fixes assertion failure
Fixes: 24ebfda03228b5cc1ef792608cfba458/signal_sigabrt_7ffff6ae7c37_6473_3fa8a111dbc752b1a7c411c5ab79aaa4.wma

Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
(cherry picked from commit 67318187)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavcodec/wmalosslessdec.c

@@ -1271,6 +1271,11 @@ static int decode_packet(AVCodecContext *avctx, void *data, int *got_frame_ptr,
         }
     }
 
+    if (remaining_bits(s, gb) < 0) {
+        av_log(avctx, AV_LOG_ERROR, "Overread %d\n", -remaining_bits(s, gb));
+        s->packet_loss = 1;
+    }
+
     if (s->packet_done && !s->packet_loss &&
         remaining_bits(s, gb) > 0) {
         /* save the rest of the data so that it can be decoded