Error installing Core v12.3 on Cygwin with OCaml 4.08.1

[mikesouthron]

I am getting the following error when trying to install core via opam on cygwin.

#=== ERROR while compiling core.v0.12.3 =======================================#
# context 2.0.3 | cygwin/x86_32 | ocaml-base-compiler.4.08.1 | https://opam.ocaml.org/#513397db
# path ~/.opam/4.08.1/.opam-switch/build/core.v0.12.3
# command ~/.opam/4.08.1/bin/dune build -p core -j 4
# exit-code 1
# env-file ~/.opam/log/core-44349-58c514.env
# output-file ~/.opam/log/core-44349-58c514.out
### output ###
# unix_stubs.c:1400:7: warning: implicit declaration of function ‘mlockall’; did you mean ‘mlock’? [-Wimplicit-function-declaration]
# [...]
# mlock
# unix_stubs.c: In function ‘unix_munlockall’:
# unix_stubs.c:1408:7: warning: implicit declaration of function ‘munlockall’; did you mean ‘munlock’? [-Wimplicit-function-declaration]
# if (munlockall() < 0)
# ^~~~~~~~~~
# munlock
# ocamlopt src/.core.objs/native/core__Iobuf.{cmx,o}
# File "src/iobuf.ml", line 1080, characters 4-62:
# 1080 | (set_bounds_and_buffer_sub [@inlined]) ~pos ~len ~src ~dst
# ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
# Warning 55: Cannot inline: Function information unavailable

[mikesouthron]

Cygwin does not implement a number of unix system interfaces, helpfully, mlockall and munlockall are 2 of them.