Mtype: apply 4.12 changes
Mtype: apply 4.12 changes

ocaml/merlin,dra27/merlin,rgrinberg/merlin,dra27/merlin,rgrinberg/merlin,rgrinberg/merlin,rgrinberg/merlin,ocaml/merlin,the-lambda-church/merlin,dra27/merlin,the-lambda-church/merlin,ocaml/merlin,ocaml/merlin,the-lambda-church/merlin,dra27/merlin