Common Lisp ports rely on an ASDF initialization file from
devel/cl-asdf. However, using devel/cl-asdf without the compiled ASDF
code provided by devel/cl-asdf-sbcl can cause issues. For instance,
SBCL may touch the filesystem during staging to generate the FASL,
violating staging rules.

Re-adding devel/cl-asdf-sbcl ensures precompiled ASDF code is available,
preventing these problems.