echo clean_env_variables.bat: Cleaning up so that no one inherits any of these values
set DEBUG_LEVEL_OPT=
set EXTRA_PARAMS=
set PROJECT_BOARD=
set PROJECT_CPU=
set USE_BOOTLOADER=
set DEFAULT_ENGINE_TYPE=
set EFI_FATAL_ERROR_PIN=
set BUILDDIR=
set DEBUG_LEVEL_OPT=
set USE_FATFS=