Log Message:
Update lang/coq to 8.0pl3

Changelog:
- Coq sources made compatible with ocaml 3.09.0 and lablgtk 2.6.0.
- The search depth argument of auto can be parameterised in the Ltac language
- Added entry constr_may_eval for tactic extensions (new syntax)
- A couple of lemmas of ZArith were renamed: O -> 0
- many bugfixes, for extraction, Ltac, tactics...