avcodec/wavpack: Fix invalid shift

Fixes: runtime error: left shift of 1 by 31 places cannot be represented in type 'int'
Fixes: 2377/clusterfuzz-testcase-minimized-6108505935183872

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
(cherry picked from commit c07af72098)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavcodec/wavpack.c

@@ -837,9 +837,9 @@ static int wavpack_decode_block(AVCodecContext *avctx, int block_no,
                 continue;
             }
             bytestream2_get_buffer(&gb, val, 4);
-            if (val[0] > 31) {
+            if (val[0] > 30) {
                 av_log(avctx, AV_LOG_ERROR,
-                       "Invalid INT32INFO, extra_bits = %d (> 32)\n", val[0]);
+                       "Invalid INT32INFO, extra_bits = %d (> 30)\n", val[0]);
                 continue;
             } else if (val[0]) {
                 s->extra_bits = val[0];