terminal-util: Set OPOST when setting ONLCR
    
    reset_terminal_fd sets certain minimum required terminal attributes
    that systemd relies on.
    
    One of those attributes is `ONLCR` which ensures that when a new line
    is sent to the terminal, that the cursor not only moves to the next
    line, but also moves to the very beginning of that line.
    
    In order for `ONLCR` to work, the terminal needs to perform output
    post-processing. That requires an additional attribute, `OPOST`,
    which reset_terminal_fd currently fails to ensure is set.
    
    In most cases `OPOST` (and `ONLCR` actually) are both set anyway, so
    it's not an issue, but it could be a problem if, e.g., the terminal was
    put in raw mode by a program and the program unexpectedly died before
    restoring settings.
    
    This commit ensures when `ONLCR` is set `OPOST` is set too, which is
    the only thing that really makes sense to do.
    
    (cherry picked from commit 9fe26523a189435d75b9d745188e09c17928d89e)