avcodec/aacdec_fixed: Fix runtime error: left shift of negative value -1

Fixes: 1535/clusterfuzz-testcase-minimized-5826695535788032

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

libavcodec/aacdec_fixed.c

@@ -125,7 +125,7 @@ static inline int *DEC_SQUAD(int *dst, unsigned idx)
 static inline int *DEC_UPAIR(int *dst, unsigned idx, unsigned sign)
 {
     dst[0] = (idx & 15) * (1 - (sign & 0xFFFFFFFE));
-    dst[1] = (idx >> 4 & 15) * (1 - ((sign & 1) << 1));
+    dst[1] = (idx >> 4 & 15) * (1 - ((sign & 1) * 2));
 
     return dst + 2;
 }
@@ -134,16 +134,16 @@ static inline int *DEC_UQUAD(int *dst, unsigned idx, unsigned sign)
 {
     unsigned nz = idx >> 12;
 
-    dst[0] = (idx & 3) * (1 + (((int)sign >> 31) << 1));
+    dst[0] = (idx & 3) * (1 + (((int)sign >> 31) * 2));
     sign <<= nz & 1;
     nz >>= 1;
-    dst[1] = (idx >> 2 & 3) * (1 + (((int)sign >> 31) << 1));
+    dst[1] = (idx >> 2 & 3) * (1 + (((int)sign >> 31) * 2));
     sign <<= nz & 1;
     nz >>= 1;
-    dst[2] = (idx >> 4 & 3) * (1 + (((int)sign >> 31) << 1));
+    dst[2] = (idx >> 4 & 3) * (1 + (((int)sign >> 31) * 2));
     sign <<= nz & 1;
     nz >>= 1;
-    dst[3] = (idx >> 6 & 3) * (1 + (((int)sign >> 31) << 1));
+    dst[3] = (idx >> 6 & 3) * (1 + (((int)sign >> 31) * 2));
 
     return dst + 4;
 }