Remove eval-when-compile for using package functions

[syohex]

Fix following byte-compile warnings.

helm-flx.el:243:1:Warning: the following functions might not be defined at runtime:
    flx-make-filename-cache, flx-score,
    helm-fuzzy-matching-default-sort-fn,
    helm-fuzzy-default-highlight-match, helm-basename

[PythonNut]

Hey thanks for making this and my sincere apologies for my massive delay in responding. I do things this way currently because I would like the dependencies (especially flx) to be lazily loaded.

I believe there is a different way to silence the warnings without actually loading the packages but I don't remember what it is at the moment.