Create meta boxes only for the taxonomies the post belongs to

[skoldin]

Changes in function meta_boxes()

Add check if the post is in taxonomy to create metaboxes only for the
taxonomies the post belongs to

Remove loop through $wp_post_types. It is not needed anymore. This saves
hundreds of iterations.

[mtekk]

I see the benefit (cleaner interface, sort of). However, there is a problem I see with this, it requires the edit page to be reloaded for the new metaboxes to be available (as a post changes membership in different taxonomies). If you're concerned about looping though too many things, there is a better way to improve this (see the commit 36ebded). Lastly, I would try to avoid relying on the $post global, especially if the action can pass it in for you.