Fix base's lower-bound constraint on ocaml

[kit-ty-kate]

#=== ERROR while compiling base.v0.16~preview.128.14+51 =======================#
# context              2.2.0~alpha~dev | linux/x86_64 | ocaml-base-compiler.4.13.1 | git+file:///home/opam/jst
# path                 ~/.opam/4.13/.opam-switch/build/base.v0.16~preview.128.14+51
# command              ~/.opam/opam-init/hooks/sandbox.sh build dune build -p base -j 255
# exit-code            1
# env-file             ~/.opam/log/base-8-22562a.env
# output-file          ~/.opam/log/base-8-22562a.out
### output ###
# (cd _build/default && /home/opam/.opam/4.13/bin/ocamlc.opt -w -40 -g -bin-annot -I src/.base.objs/byte -I /home/opam/.opam/4.13/lib/sexplib0 -I hash_types/src/.base_internalhash_types.objs/byte -I shadow-stdlib/src/.shadow_stdlib.objs/byte -no-alias-deps -open Base__ -o src/.base.objs/byte/base.cmo -c -impl src/base.ml)
# File "src/base.ml", lines 33-46, characters 4-52:
# 33 | ....module type of struct
# 34 |     include Shadow_stdlib
# 35 |   end
# 36 |   (* Modules defined in Base *)
# 37 |   with module Array := Shadow_stdlib.Array
# ...
# 43 |   with module Either := Shadow_stdlib.Either
# 44 |   with module Float := Shadow_stdlib.Float
# 45 |   with module Hashtbl := Shadow_stdlib.Hashtbl
# 46 |   with module In_channel := Shadow_stdlib.In_channel
# Error: Unbound module Shadow_stdlib.In_channel

[dkalinichenko-js]

Already done internally!