Omit underscore-prefixed meta keys from dropdown list. fixes #2316

git-svn-id: https://develop.svn.wordpress.org/trunk@5691 602fd350-edb4-49c9-b593-d223f7449a82

wp-admin/includes/template.php

@@ -378,6 +378,7 @@ function meta_form() {
 	$keys = $wpdb->get_col( "
 		SELECT meta_key
 		FROM $wpdb->postmeta
+		WHERE meta_key NOT LIKE '_%'
 		GROUP BY meta_key
 		ORDER BY meta_id DESC
 		LIMIT $limit" );