lexer_raw: add 4.12 changes
lexer_raw: add 4.12 changes

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