Add test to check behaviour of prefer-by-ref parameters

Zend/tests/pipe_operator/call_prefer_by_ref.phpt

@@ -0,0 +1,17 @@
+--TEST--
+Pipe operator accepts prefer-by-reference functions.
+--FILE--
+<?php
+
+$a = ['hello', 'world'];
+
+try {
+    $r = $a |> array_multisort(...);
+    var_dump($r);
+} catch (\Error $e) {
+  print $e->getMessage() . PHP_EOL;
+}
+
+?>
+--EXPECT--
+bool(true)