Add (more) missing doc blocks to wp-admin/includes/*.

See #32444.


git-svn-id: https://develop.svn.wordpress.org/trunk@32655 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-admin/includes/export.php

@@ -315,6 +315,12 @@ function export_wp( $args = array() ) {
 		}
 	}
 
+	/**
+	 *
+	 * @param bool   $return_me
+	 * @param string $meta_key
+	 * @return boolean
+	 */
 	function wxr_filter_postmeta( $return_me, $meta_key ) {
 		if ( '_edit_lock' == $meta_key )
 			$return_me = true;