Fix leak of servlet instances when running with SecurityManager:
a) In case when Servlet.init() or destroy() fail.
b) In case of a SingleThreadModel servlet. (fix wrong argument)

Includes the same fix for filter instances when running with SecurityManager
and an Error is thrown by destroy().

It is based on r1429186 and partly on r1428993.

git-svn-id: https://svn.apache.org/repos/asf/tomcat/tc6.0.x/trunk@1431946 13f79535-47bb-0310-9956-ffa450edef68