In WP Posts List Table class, comment_pending_count is calculated even if post_type does not support comments

[seanchayes]

When viewing a list of Posts or post_type's in WP Admin the WP Posts List Table class always calculates the get_pending_comments_num() without checking if the post type being listed has 'comments' support. This generates an unnecessary and unused query to the database.

I propose adding a post_type_supports check at this time to see if the post type support comments. If it does then calculate the pending comments num and if it does not then skip over the get_pending_comments_num() function call and do not calculate the pending comments num.

I have put together a patch that addresses this issue and will attach it to this ticket.

[SergeyBiryukov]

In 42638:

Posts, Post Types: Don't count pending comments in WP_Posts_List_Table::_display_rows() if the post type does not support comments.

Props seanchayes.
Fixes #43212.