Add ASDF-BINARY-LOCATIONS compatibility API

[Robert P. Goldman]

ASDF-output-locations does not straightforwardly provide the same functionality as one has gotten from ASDF-BINARY-LOCATIONS with no user configuration.

Suggest we should add an (ASDF:ASDF-BINARY-COMPAT-MODE &optional centralize-binaries) call that can be put in a user's lisp init file immediately after ASDF is loaded.

I believe that this should be provided before ASDF 2 is released.

[Faré (fahree)]

I implemented something in 1.660.

Robert, can you
1- test
2- fix any issues
3- document

?

[Faré (fahree)]

The code is there. Marking as Fix Committed.

Needs to be tested and documented before it's considered Released.

[Faré (fahree)]

I committed *some* documentation. Please review and test.

[Faré (fahree)]

I updated this functionality to work with the newfangled :root thingie that works on Windows.

Please try again, review and test again.

[Faré (fahree)]

Now that I think of it, adsf-binary-locations might never have worked correctly on Windows or any platform where pathname host and device matter. So I went above and beyond the call of duty in making things work according to original intention where they didn't use to work previously.