checking whether readline license is compatible with GPL-2... no
configure: WARNING: The LinuxCNC binary you are building may not be
distributable due to a license incompatibility with LinuxCNC (some portions
GPL-2 only) and Readline version 6 and greater (GPL-3 or later).
configure: error: To configure LinuxCNC in this way, you must
invoke configure with "--enable-non-distributable=yes".  Note that on
Debian-based systems, you may be able to use libreadline-gplv2-dev instead.