avcodec/dca_xll: Fix runtime error: signed integer overflow: -1073741824 * 32768 cannot be represented in type 'int'

Fixes: 629/clusterfuzz-testcase-6697457381539840

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

libavcodec/dca_xll.c

@@ -717,10 +717,10 @@ static void chs_assemble_msbs_lsbs(DCAXllDecoder *s, DCAXllChSet *c, int band)
                 int32_t *lsb = b->lsb_sample_buffer[ch];
                 int adj = b->bit_width_adjust[ch];
                 for (n = 0; n < nsamples; n++)
-                    msb[n] = msb[n] * (1 << shift) + (lsb[n] << adj);
+                    msb[n] = msb[n] * (SUINT)(1 << shift) + (lsb[n] << adj);
             } else {
                 for (n = 0; n < nsamples; n++)
-                    msb[n] = msb[n] * (1 << shift);
+                    msb[n] = msb[n] * (SUINT)(1 << shift);
             }
         }
     }