…1040)

In some places `tmp_ux` and `ux` where used in a mixed way, i.e.
`compute_fun` of constraint modules and what was fixed in #1039
- fixes bug when using globalization and cost computation
- fixes bug in globalization with slacks. Constraint was evaluated with
slack values from SQP iterate instead of values from the line search
candidate

Implementation:
- Removed all `tmp_*` pointers in SQP submodules
- Always evaluate at `ux`
- When one wants to evaluate at another iterate, these pointers have to
be temporarily set to another iterate and afterwards reset to the
nominal SQP iterate, as done in `ocp_nlp_evaluate_merit_fun` now.