avcodec/hqxdsp: Fix runtime error: signed integer overflow: -196264 * 11585 cannot be represented in type 'int'

Fixes: 1568/clusterfuzz-testcase-minimized-5944868608147456

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