Add a function to check whether a point is inside a quadrilateral
by checking the cross product of vectors with the quadrilateral
points, and the point being checked.
If the passed quadrilateral is zero-sized, no point is ever reported
to be inside it.
This will be used by the next commit when comparing the transformed
actor vertices.
[feaneron: add a commit message and remove unecessary code]
https://gitlab.gnome.org/GNOME/mutter/merge_requests/189
And add the necessary glue so those initialize a X11 clutter backend.
This should get Clutter tests that are dependent on windowing to work
again, thus they were enabled back again.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/672