avcodec/dirac_dwt: Fix several integer overflows

Fixes: runtime error: signed integer overflow: -2146071175 + -268479557 cannot be represented in type 'int'
Fixes: 5237/clusterfuzz-testcase-minimized-4569895275593728

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

libavcodec/dirac_dwt.h

@@ -93,10 +93,10 @@ void ff_spatial_idwt_slice2(DWTContext *d, int y);
 
 // shared stuff for simd optimizations
 #define COMPOSE_53iL0(b0, b1, b2)\
-    (b1 - ((int)(b0 + (unsigned)(b2) + 2) >> 2))
+    (b1 - (unsigned)((int)(b0 + (unsigned)(b2) + 2) >> 2))
 
 #define COMPOSE_DIRAC53iH0(b0, b1, b2)\
-    (b1 + ((int)(b0 + (unsigned)(b2) + 1) >> 1))
+    (b1 + (unsigned)((int)(b0 + (unsigned)(b2) + 1) >> 1))
 
 #define COMPOSE_DD97iH0(b0, b1, b2, b3, b4)\
     (int)(((unsigned)(b2) + ((int)(-b0 + 9U*b1 + 9U*b3 - b4 + 8) >> 4)))

libavcodec/dirac_dwt_template.c

@@ -49,7 +49,7 @@ static void RENAME(vertical_compose53iL0)(uint8_t *_b0, uint8_t *_b1, uint8_t *_
     TYPE *b1 = (TYPE *)_b1;
     TYPE *b2 = (TYPE *)_b2;
     for (i = 0; i < width; i++)
-        b1[i] -= (int)(b0[i] + (unsigned)b2[i] + 2) >> 2;
+        b1[i] -= (unsigned)((int)(b0[i] + (unsigned)b2[i] + 2) >> 2);
 }
 
 static av_always_inline void RENAME(interleave)(TYPE *dst, TYPE *src0, TYPE *src1, int w2,