malloc optimization consideration: don't add small chunks to unsorted bin

[k4lizen]

> Also on this topic, why are small chunks that are removed from the
> unsorted bin not being added to the fastbin if the tcache is full
> (if they are of the appropriate size)? I wonder if it was
> an intentional or accidental ommition.

Oh I guess the only way they would end up there would be through
malloc_consolidate, though it still might be good to put them back
in the fastbins?