[fpc-pascal] Timer in X11

[Marco van de Voort]

In our previous episode, Henry Vermaak said:
> > Not likely with Linux-only stuff in the same msg. That's where I stopped
> > reading pretty much.
> 
> What linux only stuff?  Since when does posix mean linux only?  Spare
> us the linux phobia, please.  Googling for timer_create bsd shows that
> at least freebsd supports this.

I was kidding. I will add a smiley next time. 

I'm not anti-changes. I just want to see them as a consistent complete set,
and not as a linux implementation with a laisez faire attitude wrt other
platforms.

I've been thinking about this myself, and if you don't want bad timers, the
most logical route would be to write a scheduler implementation where the
scheduler

1) in principle waits till the next registered event (events can be
periodical)
2) the wait can be broken (e.g. when a new event is registered, which could
theoretically fire before the current wait) because it also blocks on some
event. (waitmultiple on sources + tevent on Windows, select on events + pipe
on *nix)