Change the canonical way to include the C macros.h to <mojo/macros.h>.

examples/c/echo_client/echo_client.c

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Here is an example of the echo client using C bindings. This example avoids
 // making any dynamic allocations and uses the stack entirely by wildly
 // reserving a stack buffer, and foregoing any size-computation and copying.
 // Using it this way essentially requires the programmer to know the mojom
 // encoding order and can be error-prone, but fast.
 
 #include <assert.h>
+#include <mojo/macros.h>
 #include <stdio.h>
 #include <string.h>
 
 #include "examples/echo/echo.mojom-c.h"
 #include "mojo/public/c/bindings/buffer.h"
 #include "mojo/public/c/bindings/message.h"
-#include "mojo/public/c/system/macros.h"
 #include "mojo/public/c/system/main.h"
 #include "mojo/public/c/system/message_pipe.h"
 #include "mojo/public/c/system/result.h"
 #include "mojo/public/c/system/wait.h"
 #include "mojo/public/interfaces/application/application.mojom-c.h"
 #include "mojo/public/interfaces/application/application_connector.mojom-c.h"
 #include "mojo/public/interfaces/application/shell.mojom-c.h"
 
 // To avoid dynamic allocations, we reserve this much space as an upper-bound
 // for allocating mojo messages on the stack. This space is meant to be consumed
@@ skipping 344 matching lines @@
   MojoHandle echo_service_h =
       connect_to_service(echo_sp_h, mojo_examples_Echo__ServiceName,
                          strlen(mojo_examples_Echo__ServiceName));
 
   // 5) Call into the echo service.
   const char kEchoMsg[] = "Hello world!";
   call_echo(echo_service_h, kEchoMsg, strlen(kEchoMsg));
 
   return MOJO_RESULT_OK;
 }