Fix #71882 amendment 2: Negative ftruncate() on php://memory exhausts memory

Author: cmb69

ext/standard/tests/file/bug71882.phpt

@@ -3,9 +3,9 @@ Bug #71882 (Negative ftruncate() on php://memory exhausts memory)
 --FILE--
 <?php
 $fd = fopen("php://memory", "w+");
-ftruncate($fd, -1);
+var_dump(ftruncate($fd, -1));
 ?>
 ==DONE==
 --EXPECTF--
-Warning: ftruncate(): Negative size is not supported in %s%ebug71882.php on line %d
+bool(false)
 ==DONE==