Remove redundant code and variables from the cl-* ports.
Introduce bsd.cl-asdf.mk to automate the compilation and installation
of Common Lisp libraries using the ASDF framework.
Currently it supports building FASL files on SBCL and CLISP, to
support the ports that already exist in the ports tree.
This should help bringing in more cl-* ports from the ASDF repository
without excessive code duplication.