OutOfMemoryError when CI is ran with tracing

The CI will fail very often when tracing is enabled with some sort of OOM error.

http://ci.infinispan.org/viewType.html?buildTypeId=Infinispan_MasterHotspotJdk7trac

Looking closer this appears to be an issue with an accumulation of Threads. These threads aren't running either but rather are held in memory unneedingly. It appears that they are being retained in the log4j1.2 NDC class in it's hashtable. Upon further investigation we never call to NDC.remove which would clear up the current any dead threads.

I have created JBLOGGING-106 to fix this as well. In the mean time we shouldn't use NDC.