General cleanup, pt. III.
    
    dist/dist_digest.dist: removes obsolete dist file.
    etc/{build.usage,README.md}: updated.
    groups/000.host_tools.group:{autoconf,automake,gettext_tiny,install_strip,libtool,m4}_host: moved from groups/010.host_deps.group.
    groups/221.native_packages_dev.group:lua: moved from groups/231.native_packages_etc.group.
    groups/221.native_packages_dev.group:lua:${PKG_FORCE_AUTORECONF}: set.
    groups/231.native_packages_etc.group:{mlogin,tdnf}:${PKG_FORCE_AUTORECONF}: set.
    groups/241.native_packages_inet.group:nullmailer:${PKG_FORCE_AUTORECONF}: set.
    groups/251.native_packages_lib.group:lib{asr,gpg_error}:${PKG_FORCE_AUTORECONF}: set.
    midipix.env, etc/README.md, subr/pkg_configure_autotools.subr: adds FORCE_NO_AUTORECONF.
    subr/rtl_fileop.subr: adds ch{mod,own} fileops.
    vars/{check_updates,jamvm,lib{asr,gpg_error},lua,mlogin,tdnf}.vars: removes obsolete vars file.