context: use `update_file` instead of `normal` in `markcommitted`
This is the newer, more semantic API.
Differential Revision: https://phab.mercurial-scm.org/D11148
context: use new API instead of `normal` during fixup post status
We use `set_clean` or `update_file` depending of if we are in the middle of an
update or not.
Differential Revision: https://phab.mercurial-scm.org/D11147