make(1): revert migration from Lst_ForEachUntil to Lst_ForEach

There is a crucial difference between these functions, in that
Lst_ForEachUntil can cope with a few concurrent modifications while
iterating over the list.  This is something that Lst_ForEach doesn't do.

This difference led to a crash very early in NetBSD's build.sh.

(rillig)