`LDouble tests:8:test int conversions` fails for arm64 Darwin

[abhillman]

Failure Summary

running test-ldouble
........F
==============================================================================
Error: LDouble tests:8:test int conversions.

File "/Users/ahillman/Development/ocaml-ctypes/_build/oUnit-LDouble tests-mbp.local#00.log", line 46, characters 1-1:
Error: LDouble tests:8:test int conversions (in the log).

File "tests/test-ldouble/test_ldouble.ml", line 263, characters 1-1:
Error: LDouble tests:8:test int conversions (in the code).

expected: 4611686018427387903 but got: -4611686018427387904
------------------------------------------------------------------------------
Ran: 9 tests in: 0.00 seconds.
FAILED: Cases: 9 Tried: 9 Errors: 0 Failures: 1 Skip:  0 Todo: 0 Timeouts: 0.
make: *** [Makefile.tests:1395: run-test-ldouble] Error 1

Full log for test-ldouble

https://gist.github.com/abhillman/c9d03e6f222693fbdeb1234a7cc6db11

Commit

https://github.com/yallop/ocaml-ctypes/commit/cc3ccdd574b0deeec1dc20850a6515881db0f1ae

Other stuff

% uname -a
Darwin mbp.local 22.1.0 Darwin Kernel Version 22.1.0: Tue Sep 27 22:07:43 PDT 2022; root:xnu-8792.41.6~5/RELEASE_ARM64_T8103 arm64 arm Darwin

Environment was brought up using nix-shell --pure with this shell.nix https://gist.github.com/abhillman/6f8d1b16456f6fb9fbaa3fe235380723