Fix a testcase to ensure a constant is defined at runtime

Author: sj-i

Zend/tests/traits/constant_016.phpt

@@ -3,7 +3,11 @@ Compatibility of values of same name trait constants is checked after their cons
 --FILE--
 <?php
 
-define('CONSTANT', 2);
+// Ensure CONSTANT is defined at runtime
+function define_constant(): void {
+    eval("define('CONSTANT', 2);");
+}
+define_constant();
 
 trait TestTrait {
   public const Constant = 40 + CONSTANT;