Upstream worked around this problem by dropping the use of libtk-img in <URL: https://github.com/LinuxCNC/linuxcnc/commit/98a847899ee6bc59406bcee9fc79bac310e2bdd8 >. Thus this will be fixed in the next upload from upstream master, or Debian can fetch the patch.
-- Happy hacking Petter Reinholdtsen
