avcodec/aacsbr_fixed: Fix integer overflow in sbr_hf_assemble()

Fixes: runtime error: signed integer overflow: 2052929346 + 204817098 cannot be represented in type 'int'

This was missed in b1bef755
Fixes: 5275/clusterfuzz-testcase-minimized-5367635958038528

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

libavcodec/aacsbr_fixed.c

@@ -567,7 +567,7 @@ static void sbr_hf_assemble(int Y1[38][64][2],
                 int idx = indexsine&1;
                 int A = (1-((indexsine+(kx & 1))&2));
                 int B = (A^(-idx)) + idx;
-                int *out = &Y1[i][kx][idx];
+                unsigned *out = &Y1[i][kx][idx];
                 int shift;
                 unsigned round;