eina/hash: optimize eina_hash_find() when hash is empty.
Summary:
Check if hash is empty before computing the hash key and look inside the
hash to find data.
Note: could have called the eina_hash_population() api but didn't
because of extra function call.
Reviewers: Hermet
Reviewed By: Hermet
Subscribers: cedric, reviewers, committers
Tags: efl
Differential Revision: https://phab.enlightenment.org/D9531