Fuchsia: Use low-level prng call, add test, update test runner.

runtime/bin/platform_fuchsia.cc

 // Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "platform/globals.h"
 #if defined(TARGET_OS_FUCHSIA)
 
 #include "bin/platform.h"
 
 #include <runtime/sysinfo.h>
@@ skipping 10 matching lines @@
 char* Platform::resolved_executable_name_ = NULL;
 int Platform::script_index_ = 1;
 char** Platform::argv_ = NULL;
 
 bool Platform::Initialize() {
   return true;
 }
 
 
 int Platform::NumberOfProcessors() {
-  return mxr_get_nprocs();
+  return mxr_get_nprocs_conf();
 }
 
 
 const char* Platform::OperatingSystem() {
   return "fuchsia";
 }
 
 
 const char* Platform::LibraryPrefix() {
   return "lib";
@@ skipping 24 matching lines @@
 
 
 void Platform::Exit(int exit_code) {
   exit(exit_code);
 }
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // defined(TARGET_OS_FUCHSIA)