[PATCH] dix: make input clipping respect subpixels (#24187)

[Simon Thum]

Peter Hutterer wrote:
> /me goes and hides in the corner.
Come on, it can't be that hard for us to come up with a fix less
voluminous than a rewrite.

If, and only if, a master dev is supposed to contain the cross-screen
'axis' range (which is the 'co-ord space limit'?) AND we want relative
motion to include clipping, why not let moveRelative() have this instead:

    /* if attached, clip both x and y to the defined limits (usually
     * co-ord space limit). If it is attached, we need x/y to go over the
     * limits to be able to change screens. */
    if(dev->u.master) {
        clipAxis(dev->u.master, 0, x, &dev->last.remainder[0]);
        clipAxis(dev->u.master, 1, y, &dev->last.remainder[1]);
    }

I guess previously this was a no-op after all. It's mainly a semantics
question whether this is right.