[Gecode] Some small quirks in abs and power

[Christian Schulte]

In order to check I run examples/bench.exe which captures a great deal ;-)
But you have to be able to read the numbers, so time shoulkd not change.

 > What do you do to check the consistency of the build?
> Compile with stricter flags?
> Run some tests?

> Or do you just spot bugs in the source?

Well, is also do that, rather obviously ;-)

> The indentation issue should go away if I configure my IDE to use 2 
> spaces instead of tabs, I hope.
> 

Great