[PUSHED][PATCH] Fix configure.ac check for graphite

[Caolán McNamara]

On Thu, 2013-05-30 at 09:58 +0200, Francois Tigeot wrote:
> By default, graphite is only enabled on WINNT and Linux, which is wrong.
> 
> The only platform it isn't available on is Mac OS X. The attached patch
> reverses the check logic and only disables graphite support on this operating
> system.

ok pushed, but I can't verify that it builds under windows or has
bitrotted a little. We'll see I guess.

C.