hook_block_view() should not return null

Hi,

We are using the FacetAPI module and a Drupal theme with strict typing in parameters of preprocess hooks.

So, we are using [theme]_block_view_alter(array &$build, $block) in our theme.

However, this module is not returning an array in facetapi_block_view() and it can lead to some issue on our sites.

According to the official documentation, hook_block_view() is supposed to return an empty array instead of null.

The following one-line patch will fix this issue.

Original issue on Github: https://github.com/ec-europa/atomium/issues/113