winex11.drv: draw dashed lines for extended pens

[Evan Stade]

> The dash array is always small, there's no reason to allocate it on
> the heap, you can store an array in the pen object.

Ok

> Also there
> shouldn't be any need to store the 'ext' flag if you take it into
> account when building the array.

You need that flag to help choosing between LineOnOffDash and
LineDoubleDash in X11DRV_SetupGCForPen.

-- 
Evan Stade