[Agda] upgrading from 2.4.* to 2.5.1.1 (agda2-include-dirs problem)

[Jacques Carette]

Try as I might, I can't seem to 'unset' agda2-include-dirs.  I am not 
sure where this is coming from (definitely not my .emacs).  How can I tell?

[At least, that's my guess, as I keep getting the message
Warning (agda2): Note that the variable agda2-include-dirs is
no longer used. You may want to update your configuration. You
have at least two choices:
* Use the library management system.
* Set the include path using agda2-program-args.

One way to avoid seeing this warning is to make sure that
agda2-include-dirs is not bound. ]

I think I have set up the library management system correctly, but 
apparently not?

Jacques