deps: backport 85adf43e from libuv upstream

Original commit message:

    unix: consolidate rwlock tryrdlock trywrlock errors

    Fold EAGAIN and EBUSY into EBUSY. This makes it consistent across all
    Unix platforms and Windows.

    Refs: https://github.com/libuv/libuv/pull/525
    PR-URL: https://github.com/libuv/libuv/pull/535


Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>

PR-URL: https://github.com/nodejs/node-private/pull/54


Reviewed-By: Saúl Ibarra Corretgé <saghul@gmail.com>