`ssize_t` is 32 bits on 32 bits architectures, `off_t` is 64 bits
(because libuv builds with `-D_LARGEFILE_SOURCE`.)
Introduced in commit ca10e36149 ("linux: use copy_file_range for
uv_fs_copyfile when possible") merged in July of this year.
Fixes: https://github.com/libuv/libuv/issues/3011
PR-URL: https://github.com/libuv/libuv/pull/3028
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Richard Lau <rlau@redhat.com>
a00f80812e