Qemu doesn't yet support `SO_RCVTIMEO_NEW`/`SO_SENDTIMEO_NEW`, and it
unfortunately returns a bogus int instead of properly failing. For now,
patch qemu to fail in this case. The qemu bug is now reported
upstream [here].
[here]: https://gitlab.com/qemu-project/qemu/-/issues/885
And, when converting from nanoseconds to microseconds for the `*_OLD`
calls, round up rather than rounding down, so that the resulting timeout
is at least as long as requested.
Make the time conversion in `set_socket_linger` round up.
And, add tests for `set_socket_linger` and several other sockopt calls.
Dan Gohman