hard-dep for Qt 4.8

[Marco Martin]

On Thursday 12 January 2012, Martin Gräßlin wrote:
> Our distributions will ship 4.8 together with 4.8 and this combination
> might just be untested by the maintainers. So I strongly suggest that we
> make Qt 4.8 a dependency for master just to get the code tested and fixed
> before distros use it.
> 
> So unless there is a good reason why not to increase, I would like to see
> master depend on Qt 4.8.

yep, that is the most valid reason imo, distribution will have 4.8, no matter 
what

-- 
Marco Martin