[core] [api] Support OCaml 4.08

The changes are large due to `Pervasives` deprecation:

- the `Pervasives` module has been deprecated in favor of `Stdlib`, we
  have opted for introducing a few wrapping functions in `Util` and
  just unqualified the rest of occurrences. We avoid the shims as in
  the previous attempt.

- a bug regarding partial application have been fixed.

- some formatting functions have been deprecated, but previous
  versions don't include a replacement, thus the warning has been
  disabled.

We may want to clean up things a bit more, in particular
w.r.t. modules once we can move to OCaml 4.07 as the minimum required
version.

Note that there is a clash between 4.08.0 modules `Option` and `Int`
and Coq's ones. It is not clear if we should resolve that clash or
not, see PR #10469 for more discussion.

On the good side, OCaml 4.08.0 does provide a few interesting
functionalities, including nice new warnings useful for devs.

1 files changed, 7 insertions, 0 deletions

diff --git a/lib/util.mli b/lib/util.mli
index 8ccb4b3f08..b6347126e0 100644
--- a/lib/util.mli
+++ b/lib/util.mli
@@ -8,6 +8,13 @@
 (*         *     (see LICENSE file for the text of the license)         *)
 (************************************************************************)
 
+type 'a pervasives_ref = 'a ref
+val pervasives_ref : 'a -> 'a ref
+val pervasives_compare : 'a -> 'a -> int
+val (!) : 'a ref -> 'a
+val (+) : int -> int -> int
+val (-) : int -> int -> int
+
 (** This module contains numerous utility functions on strings, lists,
    arrays, etc. *)