WP_HTTP: Make the new 2nd parameter to WP_HTP::processHeaders()	as optional. See #21182. Fixes #25179

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git-svn-id: http://core.svn.wordpress.org/trunk@25149 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Don't set up $post_author_data in map_meta_cap() as we don't need it.

props duck_.
fixes #25177.

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git-svn-id: http://core.svn.wordpress.org/trunk@25150 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Add signup_id primary key to $wpdb->signups, and add better indexes.

props josephscott, pento, barry.
see #15004.

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git-svn-id: http://core.svn.wordpress.org/trunk@25151 1a063a9b-81f0-0310-95a4-ce76da25c4cd