avcodec/truemotion2: Fix integer overflows in tm2_high_chroma()

Fixes: runtime error: signed integer overflow: -1408475220 + -1408475220 cannot be represented in type 'int'
Fixes: 3336/clusterfuzz-testcase-minimized-5656839179993088

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

libavcodec/truemotion2.c

@@ -465,7 +465,7 @@ static inline void tm2_apply_deltas(TM2Context *ctx, int* Y, int stride, int *de
     }
 }
 
-static inline void tm2_high_chroma(int *data, int stride, int *last, int *CD, int *deltas)
+static inline void tm2_high_chroma(int *data, int stride, int *last, unsigned *CD, int *deltas)
 {
     int i, j;
     for (j = 0; j < 2; j++) {