test failure on s390x.

[plugwash]

Debian CI disocvered that your crate has a test failure on s390x. I was able to log in to a Debian porterbox and reproduce the issue with the latest git version.

---- operations::test::test_add_length stdout ----
thread 'operations::test::test_add_length' panicked at 'assertion failed: `(left == right)`
  left: `18446744073709551614`,
 right: `18446744073709551615`', src/operations.rs:369:9
stack backtrace:
   0: rust_begin_unwind
             at /usr/src/rustc-1.70.0/library/std/src/panicking.rs:578:5
   1: core::panicking::panic_fmt
             at /usr/src/rustc-1.70.0/library/core/src/panicking.rs:67:14
   2: core::panicking::assert_failed_inner
   3: core::panicking::assert_failed
             at /usr/src/rustc-1.70.0/library/core/src/panicking.rs:228:5
   4: ahash::operations::test::test_add_length
             at ./src/operations.rs:369:9
   5: ahash::operations::test::test_add_length::{{closure}}
             at ./src/operations.rs:366:26
   6: core::ops::function::FnOnce::call_once
             at /usr/src/rustc-1.70.0/library/core/src/ops/function.rs:250:5
   7: core::ops::function::FnOnce::call_once
             at /usr/src/rustc-1.70.0/library/core/src/ops/function.rs:250:5

I would guess this is an endian issue somewhere but I'm not sure exactly where.

Any advice?

[jamessan]

Duplicate of #152