avcodec/aacdec_fixed: Fix multiple runtime error: shift exponent 127 is too...

avcodec/aacdec_fixed: Fix multiple runtime error: shift exponent 127 is too large for 32-bit type 'int'

Fixes: 1762/clusterfuzz-testcase-minimized-5150981081792512

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

libavcodec/aacdec_fixed.c

@@ -415,7 +415,9 @@ static void apply_independent_coupling_fixed(AACContext *ac,
 
     c = cce_scale_fixed[gain & 7];
     shift = (gain-1024) >> 3;
-    if (shift < 0) {
+    if (shift < -31) {
+        return;
+    } else if (shift < 0) {
         shift = -shift;
         round = 1 << (shift - 1);