Use a secure logged_in_cookie when the home URL is forced HTTPS (see #27954).

see #15330.

Built from https://develop.svn.wordpress.org/trunk@28627


git-svn-id: http://core.svn.wordpress.org/trunk@28447 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Update the `$secure_logged_in_cookie` variable in the 'secure_logged_in_cookie' hook docs following [28627].

See #15330.

Built from https://develop.svn.wordpress.org/trunk@28628


git-svn-id: http://core.svn.wordpress.org/trunk@28448 1a063a9b-81f0-0310-95a4-ce76da25c4cd