Prime the comments cache in get_comments() rather than in comment_template()

[dd32]

At present, update_comment_cache() is called within comments_template(), on the result of get_comments().

Unfortunately this means that any plugins which use get_comments() and then use a function which relies upon a comment object, for example, get_comment_author_link( $comment_id ) it'll have a cache-miss and query the DB for data that we could've primed ourselves.

[rachelbaker]

Refreshed the patch so it applies cleanly. This is a small fix that appears to me to work as intended. Milestoning for 4.3

[nacin]

In 32769:

Update comment caches in WP_Comment_Query, rather than comments template.

props dd32.
fixes #31081.