1.0.28.71: two regressions from the 1.0.28. series

1.0.28.71: two regressions from the 1.0.28. series

 * from 1.0.28.51: when destructuring a constant :INITIAL-CONTENTS to
   MAKE-ARRAY, take care to quote the elements.

 * from 1.0.28.61: handle :BACK and :UP in CANONICALIZE-PATHNAME, and
   make sure they do not appear after :WILD-INFERIORS or :ABSOLUTE.
   I'm more and more concinved that MAKE-PATHNAME should canonicalize,
   though, so that these checks don't need to be carried out by users
   of pathnames -- but leaving that for later.

   ...how appropriate that it is .71 that fixes both.