fix SupplyLow flag on give/take

[Keir Novik]

On Fri, 20 Oct 2000, Stan Shebs wrote:

> Keir Novik wrote:
> > 
> > Don't we already have resupply-percent, rearm-percent, and repair-percent?
> 
> Yeah.  Right now they're only used by unit plan execution, and are
> only settable from game designs, but the intent of making them part
> of doctrine was to allow players to customize via preferences.
> It's not clear that it's all that valuable though, there's no game
> for which any are set except for tailhook.g, and there it's commented
> out with no explanation - so presumably you didn't find it all that
> helpful either?

I commented it out because it appeared to have no effect (is it
implemented?).  I think it would be useful; if resupply-percent is 50 then
many airplanes will crash because (a) the resupply command doesn't notice
that the supply base (carrier) has moved, and (b) the carrier could be
moving away from the aircraft. 

 - KN