Ensure TLD parser obtained from cache has correct value of blockExternal
(r1590036 + r1590040 + r1590065)

git-svn-id: https://svn.apache.org/repos/asf/tomcat/tc6.0.x/trunk@1593815 13f79535-47bb-0310-9956-ffa450edef68
Defensive coding around some XML activities that are triggered by web
applications and are therefore at potential risk of a memory leak.
Patch by markt.

git-svn-id: https://svn.apache.org/repos/asf/tomcat/tc6.0.x/trunk@1593821 13f79535-47bb-0310-9956-ffa450edef68