Add test for namespaced functions.

Author: Crell

Zend/tests/pipe_operator/namespaced_functions.phpt

@@ -0,0 +1,19 @@
+--TEST--
+Pipe operator handles all callable styles
+--FILE--
+<?php
+
+namespace Beep {
+  function test(int $x) {
+    print $x;
+  }
+}
+
+namespace Bar {
+    use function \Beep\test;
+
+    5 |> test(...);
+}
+?>
+--EXPECT--
+5