Change to X64 default build in tool scripts in sdk/bin

sdk/bin/pub.bat

 @echo off
 REM Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 REM for details. All rights reserved. Use of this source code is governed by a
 REM BSD-style license that can be found in the LICENSE file.
 
 rem Run pub.dart on the Dart VM. This script is only used when running pub from
 rem within the Dart source repo. The shipped SDK instead uses "pub_sdk.bat",
 rem which is renamed to "pub.bat" when the SDK is built.
 
 setlocal
@@ skipping 12 matching lines @@
 
 set VM_OPTIONS=
 
 rem We allow extra vm options to be passed in through an environment variable.
 if not "_%DART_VM_OPTIONS%_" == "__" (
   set VM_OPTIONS=%VM_OPTIONS% %DART_VM_OPTIONS%
 )
 
 rem Use the Dart binary in the built SDK so pub can find the version file next
 rem to it.
-set BUILD_DIR=%SDK_DIR%\..\build\ReleaseIA32
+set BUILD_DIR=%SDK_DIR%\..\build\ReleaseX64
 set PACKAGES_DIR=%BUILD_DIR%\packages
 set DART=%BUILD_DIR%\dart-sdk\bin\dart
 
 rem Run pub.
 set PUB="%SDK_DIR%\..\third_party\pkg\pub\bin\pub.dart"
 "%DART%" %VM_OPTIONS% --package-root="%PACKAGES_DIR%" "%PUB%" %*
 
 endlocal
 
 exit /b %errorlevel%
 
 :follow_links
 setlocal
 for %%i in (%1) do set result=%%~fi
 set current=
 for /f "usebackq tokens=2 delims=[]" %%i in (`dir /a:l "%~dp1" 2^>nul ^
                                              ^| find ">     %~n1 ["`) do (
   set current=%%i
 )
 if not "%current%"=="" call :follow_links "%current%", result
 endlocal & set %~2=%result%
 goto :eof
 
 :end