[LinuxPPS] Patch to make ppsldisc to 'go away' after 60 sec.

[Udo van den Heuvel]

Cirilo Bernardo wrote:
> You could also make ppsldisc like a daemon of its own and with its own
> startup script; this would fit in with my earlier proposal for a
> ppsldisc configuration file which could help match up a ttySN source
> with gpsM and ppsM.

Also ppsldisc could have a command line switch that makes it either stay
around or dies off after 60 seconds.