Fix https://issues.apache.org/bugzilla/show_bug.cgi?id=55309
Fix concurrency issue in TagPluginManager
PageInfo should not be a field as it is per page and there will be conflicts with concurrent compilations.
Patch provided by Sheldon Shao.

git-svn-id: https://svn.apache.org/repos/asf/tomcat/tc7.0.x/trunk@1508200 13f79535-47bb-0310-9956-ffa450edef68