merge of r7926 ENG-192 Fix for writer queue length statistic

git-svn-id: http://svn.terracotta.org/svn/ehcache@8018 b9324663-ca0f-0410-8574-be9b3887307d
MNK-5464 : complete fix - remove this assertion too

git-svn-id: http://svn.terracotta.org/svn/ehcache@8019 b9324663-ca0f-0410-8574-be9b3887307d
MNK-5447 : make the SizeOfTest more adaptable to a variety of platforms

git-svn-id: http://svn.terracotta.org/svn/ehcache@8020 b9324663-ca0f-0410-8574-be9b3887307d