Fixes: signed integer overflow: 32 * 553590816 cannot be represented in type 'int'
Fixes: 50993/clusterfuzz-testcase-minimized-ffmpeg_dem_WAV_fuzzer-6564974517944320
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 4075f0cec1)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>