Issues with sndioctl -m output

Hi!

As a stopgap measure before I try to integrate sndioctl into my status
bar using libsndio, I decided to try and write a simple parsing script
using sndioctl. Calling `sndioctl -m` and sed'ing around that to get a
number seemed like a straightforward approach that would avoid having to
run `sndioctl` in a loop, but unfortunately `sndioctl -m` behaves
weirdly when its output is piped into some other program. This can be
reproduced by comparing the outputs of:

    sndioctl -m

and

    sndioctl -m | cat

Not only is the initial output different, but the second case doesn't
output new messages for changes such as output level. I tried looking
into how these values are printed, but couldn't find anything obvious in
the code that would lead to this. If there are any suggestions for where
this error could be happening, I would be happy to try and fix it myself
and submit a patch.

Thanks,
Érico Nogueira