avcodec/cavsdec: Fix runtime error: signed integer overflow: 59 + 2147483600 cannot be represented in type 'int'

Fixes: 1903/clusterfuzz-testcase-minimized-5359318167715840

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

libavcodec/cavsdec.c

@@ -615,7 +615,7 @@ static inline int decode_residual_inter(AVSContext *h)
 
     /* get quantizer */
     if (h->cbp && !h->qp_fixed)
-        h->qp = (h->qp + get_se_golomb(&h->gb)) & 63;
+        h->qp = (h->qp + (unsigned)get_se_golomb(&h->gb)) & 63;
     for (block = 0; block < 4; block++)
         if (h->cbp & (1 << block))
             decode_residual_block(h, &h->gb, inter_dec, 0, h->qp,