[LEAPSECS] more poison in the NTP pool

[Paul Sheer]

> 

> It seems from this that there are always a few people advertising

> leap seconds when they shouldn't be...

> 



previously i proposed that any code that measures a fail-timeout make
that timeout 1000ms longer whenever  t % 86400  is near zero

this pattern would duck most bugs

these bogus advertisements seem like another good reason to implement
this

-paul