Use ocaml-compiler-libs package

[EduardoRFS]

Currently when importing ocaml-migrate-parsetree all the packages under compilerlibs.common are added to the environment, this is problematic when there is copies of OCaml code, because now the error messages are always Types/1.signature not Types/2.signature, using ocaml-compiler-libs solves that.

If no one is against this I will implement it in the following days.