Enhance the MachMessageServer test to cover large messages (MACH_RCV_LARGE)

util/mach/mach_message_server.h

Index: util/mach/mach_message_server.h
diff --git a/util/mach/mach_message_server.h b/util/mach/mach_message_server.h
index c77fb324222eba7de054c3b63400333b534fc0bb..3b08a55d577c399e31c480029958245a8c67e044 100644
--- a/util/mach/mach_message_server.h
+++ b/util/mach/mach_message_server.h
@@ -121,7 +121,8 @@ class MachMessageServer {
   //!     MachMessageServerInterface::MachMessageServerFunction() is called to
   //!     handle the request and populate the reply.
   //! \param[in] receive_port The port on which to receive the request message.
-  //! \param[in] options Options suitable for mach_msg.
+  //! \param[in] options Options suitable for mach_msg. For the defaults, use
+  //!     `MACH_MSG_OPTION_NONE`.
   //! \param[in] persistent Chooses between one-shot and persistent operation.
   //! \param[in] nonblocking Chooses between blocking and nonblocking operation.
   //! \param[in] timeout_ms When \a nonblocking is `false`, the the maximum