message: Make FunctionExtent repr(C) and Debug.
diff: @@ -221,6 +221,8 @@ impl Drop for GlobalFrameInfoRegistration {
  /// Represents a continuous region of executable memory starting with a function
  /// entry point.
  +#[derive(Debug)]
  +#[repr(C)]
  pub struct FunctionExtent {
  /// Entry point for normal entry of the function. All addresses in the
  /// function lie after this address.
  