For clarity, initialize some arrays that previously were only assigned via short circuit in loops.

See #30799.


git-svn-id: https://develop.svn.wordpress.org/trunk@30982 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-admin/includes/upgrade.php

@@ -1786,7 +1786,7 @@ function dbDelta( $queries = '', $execute = true ) {
 
 		if ($tableindices) {
 			// Clear the index array.
-			unset($index_ary);
+			$index_ary = array();
 
 			// For every index in the table.
 			foreach ($tableindices as $tableindex) {