Forward referenced classoid-cells can now be loaded from FASLs.

When
(defun x (x)
  (typep x 'bar))

(defclass bar ()
  ())

is compiled twice, the typecheck is optimized and a classoid-cell is
dumped into the FASL, but upon load in a new instance it's
reconstructed using FIND-CLASSOID-CELL with :errorp t, resulting in an
error, defeating the stated reason for indirection.

Fixes lp#746132.