get_pages() should accept 'any' among it's post_status arg

[pbiron]

WP_Query::get_posts() accepts 'any' among it's $post_status $query_vars and I think get_pages() should do the same.

I've combed through the 4.7.4 core code and can't find any place where this enhancement would break existing code.

[pbiron]

FYI: The patch I've attached is loosely based on how 'any' is handled in WP_Query()::get_posts(), but since get_pages() is implemented very differently from WP_Query::get_posts() is kind of different.

[pbiron]

The note about me combing through the 4.7.4 core code is my signal that someone who knows the history of how get_pages() has been used in core in previous versions should check that my patch doesn't break previous versions of core if this patch would be backported.

[pbiron]

My immediate need for this request is a use of wp_dropdown_pages() on a post_type that uses custom post_stati and I was surprised to learn that I couldn't use 'any' to include posts with these custom post stati.

[spacedmonkey]

@pbiron This patch will have to be refreshed now #12821 has been committed.