Well, the existing easyconfigs broke because this was set to `False` by default.

In the future, we should determine whether these `libint` and `libxc` parameters are still useful. Why not build against `libxc` simply based on the fact whether it's there as a dep or not?

Now you need to both add it as a dep, and set `libxc` to True, which is just stupid.

Simply dropping these two shouldn't break anything, EB just ignores unknown entries in the easyconfig file...