Add CHECK/SUINT code

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
(cherry picked from commit 4614bf2caf)
(cherry picked from commit e8d4eacc07)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavutil/internal.h

@@ -30,6 +30,10 @@
 #    define NDEBUG
 #endif
 
+#if defined(DEBUG) && !defined(CHECKED)
+#    define CHECKED
+#endif
+
 #include <limits.h>
 #include <stdint.h>
 #include <stddef.h>
@@ -258,6 +262,16 @@ void avpriv_request_sample(void *avc,
 #   define ff_dlog(ctx, ...) do { if (0) av_log(ctx, AV_LOG_DEBUG, __VA_ARGS__); } while (0)
 #endif
 
+// For debuging we use signed operations so overflows can be detected (by ubsan)
+// For production we use unsigned so there are no undefined operations
+#ifdef CHECKED
+#define SUINT   int
+#define SUINT32 int32_t
+#else
+#define SUINT   unsigned
+#define SUINT32 uint32_t
+#endif
+
 /**
  * Clip and convert a double value into the long long amin-amax range.
  * This function is needed because conversion of floating point to integers when