avcodec/qoadec: Fix undefined overflow in lms_predict

Fixes: signed integer overflow: -1575944192 + -602931200 cannot be represented in type 'int'
Fixes: 62285/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_QOA_fuzzer-6470469339185152

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

libavcodec/qoadec.c

@@ -67,7 +67,7 @@ static int qoa_lms_predict(QOAChannel *lms)
 {
     int prediction = 0;
     for (int i = 0; i < QOA_LMS_LEN; i++)
-        prediction += lms->weights[i] * lms->history[i];
+        prediction += (unsigned)lms->weights[i] * lms->history[i];
     return prediction >> 13;
 }