Revert "MSVC build: Avoid using zstd MSYS program"

This reverts commit e247836.

It's okay for this to happen as long as they are on same version.
Also it's the only way to get zstd support in clc for now.

buildscript/modules/winflexbison.cmd

@@ -7,8 +7,4 @@
 @set flexloc=%devroot%\flexbison
 @IF %flexstate%==1 IF NOT EXIST "%devroot%\flexbison\win_flex.exe" set flexloc=%msysloc%\usr\bin
 @IF %flexstate%==1 IF NOT EXIST "%devroot%\flexbison\win_flex.exe" IF NOT EXIST "%msysloc%\usr\bin\flex.exe" set flexstate=0
-@endlocal&set flexstate=%flexstate%&set flexloc=%flexloc%
-@IF %flexstate%==1 IF "%flexloc%"=="%msysloc%\usr\bin" IF EXIST "%msysloc%\flexbison\" RD /S /Q "%msysloc%\flexbison"
-@IF %flexstate%==1 IF "%flexloc%"=="%msysloc%\usr\bin" ROBOCOPY "%msysloc%\usr" "%msysloc%\flexbison" /E
-@IF %flexstate%==1 IF "%flexloc%"=="%msysloc%\usr\bin" IF EXIST "%msysloc%\flexbison\bin\zstd.exe" del "%msysloc%\flexbison\bin\zstd.exe"
-@IF %flexstate%==1 IF "%flexloc%"=="%msysloc%\usr\bin" set flexloc=%msysloc%\flexbison\bin
+@endlocal&set flexstate=%flexstate%&set flexloc=%flexloc%