more kaffe-0.8.x garbage collection problems (at least on m68k)

[Esa Salonen]

After my previous patch for struct _constants, the non incremental
gc seems to work OK, but the incremental mode seems to leave some
garbage, and after a while i get:
(I periodically start gc manually using System.gc() in my test code,
because incremental mode don't seem to start the actual collection at all ?)

<GC: total 1046K, alloc 400K, marked 646K, freeing 399K>
./jit/code-analyse.c:212 sp >= meth->localsz && sp <= meth->localsz + meth->stac
ksz -- assertion failed

Should the incremental mode work as well as the non incremental mode ?