dvbsnoop

Piping the output of 'dvbsnoop' to other processes on recent versions of
Linux had some unexpected results, essentially the dvbsnoop output was
buffed up to ~30 lines at a time before being flushed to the next process.
This messed up my simple line-parser as all the lines arrived at the same
time. This patch uses setvbuf/setlinebuf to disable line-buffering of the
dvbsnoop output.

Regards,
MC