anchor.diff:  echo Swtich to x86 build env
   cd luajit\src
   call msvcbuild.bat
  -copy /Y lua51.dll ..\..\prebuilt\x86\slua.dll
  +copy /Y lua51.dll ..\..\prebuilt\win\x86\slua.dll
   cd ..\..
   
   call "%ENV64%"
   echo Swtich to x64 build env
   cd luajit\src
   call msvcbuild.bat
  -copy /Y lua51.dll ..\..\prebuilt\x64\slua.dll
  +copy /Y lua51.dll ..\..\prebuilt\win\x64\slua.dll
   cd ..\..
   
   
  
positive.code: if exist "%VS140COMNTOOLS%" (
  	set VCVARS="%VS140COMNTOOLS%..\..\VC\bin\"
  	goto build
  	) 
  else (goto missing)
  
  :build
  
negative.code: 
  :missing
  echo Can't find Visual Studio 2015.
  goto :eof
  