Fix build break (true is not defined on windows for C).

runtime/bin/test_extension.c

 /* Copyright (c) 2012, 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 <assert.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 
 #include "include/dart_api.h"
@@ skipping 24 matching lines @@
 Dart_NativeFunction ResolveName(Dart_Handle name,
                                 int argc,
                                 bool* auto_setup_scope) {
   /* assert(Dart_IsString(name)); */
   const char* c_name;
   Dart_Handle check_error;
 
   if (auto_setup_scope == NULL) {
     return NULL;
   }
-  *auto_setup_scope = true;
+  *auto_setup_scope = 1;
   check_error = Dart_StringToCString(name, &c_name);
   if (Dart_IsError(check_error)) {
     Dart_PropagateError(check_error);
   }
   if ((strcmp("TestExtension_IfNull", c_name) == 0) && (argc == 2)) {
     return IfNull;
   }
   if ((strcmp("TestExtension_ThrowMeTheBall", c_name) == 0) && (argc == 1)) {
     return ThrowMeTheBall;
   }
   return NULL;
 }
 
 
 /* Native entry point for the extension library. */
 DART_EXPORT Dart_Handle test_extension_Init(Dart_Handle parent_library) {
   Dart_Handle result_code;
   if (Dart_IsError(parent_library)) {
     return parent_library;
   }
 
   result_code = Dart_SetNativeResolver(parent_library, ResolveName);
   if (Dart_IsError(result_code)) {
     return result_code;
   }
 
   return parent_library;
 }