anchor.diff:  @echo %toolset% > %mesa%toolset-%abi%.ini
   
   :prep_mesa
  +@set PATH=%oldpath%
   @cd %mesa%
   @set mesapatched=0
   @set branch=none
  
positive.code: @set vsenv=%vsenv14%
  @if %toolset%==15 set vsenv=%vsenv15%
  @set PATH=%mesa%flexbison\;%PATH%
  @TITLE Building Mesa3D %abi%
  
  :build_llvm
  
negative.code: @if EXIST build\windows-%longabi% set /p cleanbuild=Do you want to clean build (y/n):
  @if EXIST build\windows-%longabi% echo.
  @if /I "%cleanbuild%"=="y" RD /S /Q build\windows-%longabi%
  @cd %mesa%mesa
  @echo.
  
  :build_mesa_exec
  @%sconscmd%
  