message: Use enum to define kTfLiteNullBufferHandle instead of const.
diff: @@ -50,6 +50,8 @@ typedef enum {
  kTfLiteMaxExternalContexts = 3
  } TfLiteExternalContextType;
  +struct TfLiteContext;
  +
  // An external context is a collection of information unrelated to the TF Lite
  // framework, but useful to a subset of the ops. TF Lite knows very little
  // about about the actual contexts, but it keeps a list of them, and is able to
  @@ -279,7 +281,9 @@ typedef enum {
  // The delegates should use zero or positive integers to represent handles.
  // -1 is reserved from unallocated status.
  typedef int TfLiteBufferHandle;
  -const TfLiteBufferHandle kTfLiteNullBufferHandle = -1;
  +enum {
  + kTfLiteNullBufferHandle = -1,
  +};
  // An tensor in the interpreter system which is a wrapper around a buffer of
  // data including a dimensionality (or NULL if not currently defined).
  