The lua loader is quite mature, and /boot is getting a bit cluttered.
Allow removing the forth loader with make delete-old if WITHOUT_FORTH
is set, instead of the previous behavior of only removing the doc.
As usual, please be suspicious; I have no idea what I'm doing. I have
been deleting these files for a while, and have tested this as well.
It makes /boot a lot more managable by being viewable with ls in one
window of 80x25. Particularly, I suspect .so is a library so I put that
under make delete-old-libs.
MFC: no, i dont think so since this is a breaking change of behavior