dirstate: replace `_add` call in `setparent`
Same logic as the previous changeset, it get us closer to removed older API on
the dirstate.
Differential Revision: https://phab.mercurial-scm.org/D11425
dirstate: directly call the right function in `set_tracked`
This get use closer to removing some older API on the dirstate.
Differential Revision: https://phab.mercurial-scm.org/D11424