[patches] [vtab 1/1] Add ephemeral truncate method to space vtab

[n.pettik]

Well, personally I would prefer the last variant: anyway this truncate             
function is needed to be called only before space_delete(). So it would            
be logical to gather them into one method. Thus, the proposal is           
to add space_delete_epehemeral(struct space *) which calls 
cleanup/destroy ephemeral from vtab (or whatever it would be called, 
but for memtx it does the same routine as prune does) and calls space_delete().
Did I get it right?