message: Go: Don't require -std=c99 for the cgo code.
  This should fix the error:
  github.com/tensorflow/tensorflow/tensorflow/go/graph.go:31:3: error:
  'for' loop initial declarations are only allowed in C99 mode
  //  for (int i = 0; i < num_shapes; i++) {
  ^
  in some continuous builds like:
diff: @@ -28,7 +28,8 @@ package tensorflow
  // int num_shapes) {
  // const int64_t** dims =
  // (const int64_t**)malloc(sizeof(const int64_t*) * num_shapes);
  -// for (int i = 0; i < num_shapes; i++) {
  +// int i = 0;
  +// for (i = 0; i < num_shapes; i++) {
  // dims[i] = flat_dims;
  // if (num_dims[i] > 0) {
  // // flat_dims will be NULL iff num_shapes is 0 or all elements in num_dims are <= 0.
  