Fix debug.impure.lisp / BUG-310175 for :stack-allocatable-lists targets.
* Not all platforms stack-allocate. Some platforms (PPC) stack-
allocate some things, but not most things.
* PPC, in particular, stack allocates for LIST and LIST* (the
:stack-allocatable-lists feature), but doesn't stack allocate for
CONS. And it turns out that the compiler transforms one-arg-LIST
and two-arg-LIST* to CONS.
* Use two-arg-LIST to force the :stack-allocatable-lists code
path, and mark the test as failing on non-:stack-allocatable-lists