groups/2*.native_packages_*.group: adds dependencies.
    subr/build_init.subr:buildp_init_getopts(): reject invalid build group names.
    subr/build_init.subr:buildp_init_prereqs(): insist on GNU sed.
    subr/build_init.subr:build_fini(): fixed.
    subr/ex_rtl_complex.subr:ex_rtl_kill_tree(): restored.
    subr/ex_rtl_log.subr: include fallback ${DEFAULT_LOG_MSG_*_COLOUR}s.