Skip and fix test for HHVM with ReadConcerns

Author: derickr

tests/query/query-ctor_error-001.phpt

@@ -39,5 +39,5 @@ Expected "readConcern" option to be MongoDB\Driver\ReadConcern, array given
 OK: Got MongoDB\Driver\Exception\InvalidArgumentException
 Expected "readConcern" option to be MongoDB\Driver\ReadConcern, object given
 OK: Got MongoDB\Driver\Exception\InvalidArgumentException
-Expected "readConcern" option to be MongoDB\Driver\ReadConcern, null given
+Expected "readConcern" option to be MongoDB\Driver\ReadConcern, %r(null|NULL)%r given
 ===DONE===

tests/readConcern/readconcern-ctor_error-002.phpt

@@ -2,6 +2,7 @@
 MongoDB\Driver\ReadConcern construction (invalid level type)
 --SKIPIF--
 <?php require __DIR__ . "/../utils/basic-skipif.inc"; ?>
+<?php if (defined("HHVM_VERSION_ID")) exit("skip HHVM throws Exception instead of InvalidArgumentException"); ?>
 --FILE--
 <?php
 require_once __DIR__ . "/../utils/basic.inc";