In order to properly read from /dev/kmsg, we need [*]:
1) open /dev/kmsg with O_NONBLOCK
2) handle the EAGAIN/WouldBlock error as end of records
3) treat '\n' (and not '\0') as record separator.
4) do lseek(fd, 0, SEEK_DATA)
Because Windows doesn't support O_NONBLOCK and SEEK_DATA, we had protect
these code with #[cfg(not(target_os = "windows"))]. Moreover because
Windows doesn't have /dev/kmsg, it is mandatory to use the '-K' switch.
[*] https://www.kernel.org/doc/Documentation/ABI/testing/dev-kmsg
98ef2d7f82