Replace x() by isset(), !empty() or defaults()

- Remove extraneous parentheses around empty() calls
- Remove duplicate calls to intval(), count() or strlen() after empty()
- Replace ternary operators outputting binary value with empty() return value
- Rewrite defaults() without x()

src/Database/DBStructure.php

@@ -538,7 +538,7 @@ class DBStructure
 		$primary_keys = [];
 		foreach ($structure["fields"] AS $fieldname => $field) {
 			$sql_rows[] = "`".DBA::escape($fieldname)."` ".self::FieldCommand($field);
-			if (x($field,'primary') && $field['primary']!='') {
+			if (!empty($field['primary'])) {
 				$primary_keys[] = $fieldname;
 			}
 		}