Allow using a system-installed giflib

[Brad Wetmore]

On 4/11/2013 3:45 AM, Alan Bateman wrote:

> Personally I think it would be good to agree and set a date, after which
> there is no requirement to keep the old build "working". At the moment
> it is a tax on all changes that involve change changes. I'm not even
> sure that the old build generates good bits as I don't know of any
> testing that is done with the old build now.

That would be fine with me, now that my JDK 8 work is mostly over.

Things may finally quiet down a bit and can work with build-dev to make 
the JCE builds more usable.

Brad