avcodec/apedec: Fix integer overflow in filter_3800()

Fixes: signed integer overflow: -2147448926 + -198321 cannot be represented in type 'int'
Fixes: 48798/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_APE_fuzzer-5739619273015296
Fixes: 48798/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_APE_fuzzer-6744428485672960

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

libavcodec/apedec.c

@@ -934,7 +934,7 @@ static av_always_inline int filter_3800(APEPredictor *p,
     p->coeffsB[filter][0] += (((d3 >> 29) & 4) - 2) * sign;
     p->coeffsB[filter][1] -= (((d4 >> 30) & 2) - 1) * sign;
 
-    p->filterB[filter] = p->lastA[filter] + (predictionB >> shift);
+    p->filterB[filter] = p->lastA[filter] + (unsigned)(predictionB >> shift);
     p->filterA[filter] = p->filterB[filter] + (unsigned)((int)(p->filterA[filter] * 31U) >> 5);
 
     return p->filterA[filter];