Update build_dist.bat

Do not remove build and dist folders (purpose of the clean_up.bat script)

Author: PierreRaybaut

scripts/build_dist.bat

@@ -10,11 +10,9 @@ call %~dp0utils GetScriptPath SCRIPTPATH
 call %FUNC% GetLibName LIBNAME
 cd %SCRIPTPATH%\..\
 if exist MANIFEST ( del /q MANIFEST )
-if exist build ( rmdir /s /q build )
-if exist dist ( rmdir /s /q dist )
 call %FUNC% SetPythonPath
 call %FUNC% UseWinPython
 python setup.py sdist bdist_wheel --universal
 python setup.py build sdist
 rmdir /s /q %LIBNAME%.egg-info
-call %FUNC% EndOfScript
+call %FUNC% EndOfScript