I am being indecisive about this param.  Just verified that it is no longer in active use.  So only impact would be to community users that have leveldb, but not eleveldb / riak.  Would cause their compile to break on update ... which might be a good thing since it screams "something has changed".  I intentionally did not remove "block_cache" because Google has some special configurations in the unit tests that set the value directly (i.e. not via double_cache).  Open to opinions / direction on max_open_files.