Fix var_export for resources

Debug builds hit an assert, and release builds would output
something like array(}.

hphp/runtime/base/variable_serializer.cpp

@@ -69,6 +69,7 @@ void VariableSerializer::getResourceInfo(String &rsrcName, int &rsrcId) {
 void VariableSerializer::setResourceInfo(CStrRef rsrcName, int rsrcId) {
   m_rsrcName = rsrcName;
   m_rsrcId = rsrcId;
+  m_objCode = 0;
 }
 
 String VariableSerializer::serialize(CVarRef v, bool ret) {
@@ -849,7 +850,7 @@ void VariableSerializer::writeArrayFooter() {
   case Type::VarExport:
   case Type::PHPOutput:
     indent();
-    if (info.is_object) {
+    if (info.is_object && m_objCode) {
       if (m_objCode == 'O') {
         m_buf->append("))");
       } else {

hphp/test/slow/var_export/resource.php

@@ -0,0 +1,8 @@
+<?php
+
+function test() {
+  $f = fopen(__FILE__, "r");
+  var_export($f);
+}
+
+test();

hphp/test/slow/var_export/resource.php.expect

@@ -0,0 +1,2 @@
+array (
+)