[project @ 2000-06-13 15:35:29 by sof]

On mingw32, which is the only 'platform' where we support producing
DLLs, prefix each static closure with a zero word. This is needed so
that we can distinguish between pointers to (reversed!) info tables
and static closures just by checking whether there's a zero word just
above the pointed-to entity. Wish there was a better way..