It seems like most of the times, timeout == 0 means "use the default
timeout". However, at least with the sectionsd eit update filter and
the PMT version update filter, timeout == 0 means really "no timeout"
alas "infinite". Work around this by using the default timeout only
if no negative filtermask is given.
This fixes the "EPG on program change" (and PMT update probably, too).