[DGD] Correction on rlimits behavior.

[Raymond Jennings]

Anyone who was under the impression that inner rlimits gets a fresh supply
of ticks that doesn't count against outer limits, please be advised:

I just had a discussion with dworkin about it, and apparently that is NOT
how things are actually working, or supposed to work.

The correct behavior is that the outer rlimit's remaining ticks gets passed
inside to the inner rlimits, and when the inner rlimits are done, any
leftover ticks are given back to the outer rlimits.

The reason being is that if the remaining ticks were simply forked and
forgotten, it would be possible for the inner rlimits to burn ticks for
free without properly taking them out of the outer rlimits tick budget.

This way, inner rlimits doesn't get to cheat.

There were a couple comments on this on the list, and this post is a
correction.