Fix more installation discrepancies in scripts directory * scripts/module.mk (scripts_@ftpdir): Fix definition. (install-pkg-add): Strip "scripts/" prefix when installing PKG_ADD files. * scripts/set/module.mk (FCN_FILE_DIRS): Add scripts/set/private. (scripts_set_FCN_FILES) Remove scripts/set/private/validsetargs.m from the list. (scripts_set_PRIVATE_FCN_FILES, scripts_set_privatedir, scripts_set_private_DATA): New variables. (FCN_FILES): Add $(scripts_set_PRIVATE_FCN_FILES) to the list. * scripts/startup/module.mk (scripts_startup_DATA) Remove $(STARTUP_FILE_SRC) from the list.