LdapLink::sweep shouldn't free smart allocated objects

LdapLink::sweep, avoid freeing smart allocated objects

Closes #1644

Reviewed By: @ptarjan

Differential Revision: D1144565

Pulled By: @scannell

hphp/runtime/ext/ext_ldap.cpp

@@ -67,7 +67,10 @@ public:
   LDAP *link;
   Variant rebindproc;
 };
-IMPLEMENT_OBJECT_ALLOCATION(LdapLink)
+
+void LdapLink::sweep() {
+  close();
+}
 
 class LdapResult : public SweepableResourceData {
 public: