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.
The asdf-init.lisp script was changed to support the bundled ASDF
libraries in lang/ccl and lang/sbcl. Therefore, it can be safely
loaded by both (also by lang/clisp) to enable the ASDF framework.
