Add thunks for wait set operations, together with public tests.

mojo/public/c/system/tests/wait_unittest.cc

 // 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.
 
 // This file tests the C wait API (the functions declared in
 // mojo/public/c/system/wait.h).
 
+#include "mojo/public/c/system/wait.h"
+
 #include "mojo/public/c/system/handle.h"
 #include "mojo/public/c/system/result.h"
-#include "mojo/public/c/system/wait.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace {
 
 TEST(WaitTest, InvalidHandle) {
   EXPECT_EQ(MOJO_RESULT_INVALID_ARGUMENT,
             MojoWait(MOJO_HANDLE_INVALID, ~MOJO_HANDLE_SIGNAL_NONE, 1000000u,
                      nullptr));
 
   const MojoHandle h = MOJO_HANDLE_INVALID;
   MojoHandleSignals sig = ~MOJO_HANDLE_SIGNAL_NONE;
   EXPECT_EQ(
       MOJO_RESULT_INVALID_ARGUMENT,
       MojoWaitMany(&h, &sig, 1u, MOJO_DEADLINE_INDEFINITE, nullptr, nullptr));
 }
 
 // TODO(vtl): Write tests that actually test waiting.
 
 }  // namespace