Atari ST/m68k: fix 68010->68060 compatibility

[cstrotm]

VolksForth crashes on m68k CPUs other than the 68000. We need to find out where it goes wrong.

Possibly we create a generic m68k target first, fix it there and then backport to the Atari ST target

[polluks]

See https://retrocomputing.stackexchange.com/questions/6647/are-later-68000-variants-backward-compatible-with-earlier-ones