Changes to FastRemovalDequeue:

Changes to FastRemovalDequeue:
- Make queue thread safe and remove external synchronisation
- Provide maximal size to queue
- Include size checking when adding entries
- Return handle to displaced entries when queue overflows
  while adding a new entry
- Explicitely invalidate queue entries on removal by using
  new field "valid"

Changes to JspRuntimeContext:
- Initialize FastRemovalDequeue with correct size
- No more external synchronisation for FastRemovalDequeue
- Private utility method to unload a wrapper
- Check for displaced wrapper when adding a new wrapper
  to the queue and unload it

Changes to JspServletWrapper:
- No more explicit overflow check for the queue. It's now
  done implicitely when adding to the queue.

git-svn-id: https://svn.apache.org/repos/asf/tomcat/trunk@1028935 13f79535-47bb-0310-9956-ffa450edef68