avcodec/wmaprodec: Fixes integer overflow with 32bit samples

Fixes: left shift of 1 by 31 places cannot be represented in type 'int'
Fixes: 18860/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_WMAPRO_fuzzer-5755223125786624

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

libavcodec/wmaprodec.c

@@ -544,7 +544,7 @@ static av_cold int decode_init(WMAProDecodeCtx *s, AVCodecContext *avctx, int nu
     for (i = 0; i < WMAPRO_BLOCK_SIZES; i++)
         ff_mdct_init(&s->mdct_ctx[i], WMAPRO_BLOCK_MIN_BITS+1+i, 1,
                      1.0 / (1 << (WMAPRO_BLOCK_MIN_BITS + i - 1))
-                     / (1 << (s->bits_per_sample - 1)));
+                     / (1ll << (s->bits_per_sample - 1)));
 
     /** init MDCT windows: simple sine window */
     for (i = 0; i < WMAPRO_BLOCK_SIZES; i++) {