Makefile: Empty default ASDF registries when using internal Quicklisp.
Makefile: Empty default ASDF registries when using internal Quicklisp.

This makes sure ASDF does not accidentally load a system-wide Common Lisp
library which could conflict with the internal Quicklisp distribution or the Git
submodules.

jmercouris/NeXT,jmercouris/NeXT