COSQLiteStore: Workaround for libobjc2 not supporting blocks that case self to be retained/released inside of -dealloc

git-svn-id: http://svn.gna.org/svn/etoile/trunk/Etoile/Frameworks/CoreObject@10474 7b3f36aa-e6db-49c1-8b4c-66eac1997e64