This is an update of the lang/ocaml port to the newest upstream version, 3.12.0.

Highlights in this new release include:
 
* Polymorphic recursion is supported, using explicit type declarations on the recursively-defined identifiers.
* First-class modules: module expressions can be embedded as values of the core language, then manipulated like any other first-class value, then projected back to the module level.
* New operator to modify a signature a posteriori: S with type t := tau denotes signature S where the t type component is removed and substituted by the type tau elsewhere.
* New notations for record expressions and record patterns: { lbl } as shorthand for { lbl = lbl }, and { ...; _ } marks record patterns where some labels were intentionally omitted.
* Local open let open ... in ... now supported by popular demand.
* Type variables can be bound as type parameters to functions; such types are treated like abstract types within the function body, and like type variables (possibly generalized) outside.
* The module type of construct enables to recover the module type of a given module.
* Explicit method override using the method! keyword, with associated warnings and errors.

Fix: Patch to the port directory included. (no great changes; one patch slightly modified and that's it)

Patch attached with submission follows:
How-To-Repeat: n/a