Rationalize mojo_public_*tests targets.

mojo/public/c/system/tests/perftest_utils.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.
 
 #include "mojo/public/c/system/tests/perftest_utils.h"
 
 #include <assert.h>
 #include <stddef.h>
 #include <time.h>
 
+#include "mojo/public/c/system/macros.h"
 #include "mojo/public/c/system/time.h"
-#include "mojo/public/cpp/system/macros.h"
 #include "mojo/public/cpp/test_support/test_support.h"
 
 namespace mojo {
 namespace test {
 
 // Iterates the given function for |kPerftestTimeMicroseconds| and reports the
 // number of iterations executed per second.
 void IterateAndReportPerf(const char* test_name,
                           const char* sub_test_name,
                           std::function<void()> single_iteration) {
@@ skipping 21 matching lines @@
       static_cast<time_t>(microseconds / 1000000),       // Seconds.
       static_cast<long>(microseconds % 1000000) * 1000L  // Nanoseconds.
   };
   int rv = nanosleep(&req, nullptr);
   MOJO_ALLOW_UNUSED_LOCAL(rv);
   assert(rv == 0);
 }
 
 }  // namespace test
 }  // namespace mojo