asdf for gcl

[Raymond Toy]

Gcl 2.7.1 can run asdf now, with a few minor changes to the asdf code. 
The changes should be included with asdf soon. This is pretty good news! 
It would be nice if gcl next would include a copy of asdf so it’s 
immediately available with gcl. Most other lisps do this already. 
Usually a simple |(require :asdf)| will load asdf into lisp.

I hope gcl can do this too in the next release, especially as a fasl 
since it takes gcl quite a bit of time to compile asdf.lisp.

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