[RF] Properly close polygons when drawing PDFs as surfaces.
[RF] Properly close polygons when drawing PDFs as surfaces.

[ROOT-10931] Due to an unstable sorting algorithm, polygons sometimes
won't close, since the order of the outermost points is not preserved.
By moving those points by 1/1000 of the distance between points, they
now always close.

root-mirror/root,olifre/root,root-mirror/root,olifre/root,olifre/root,karies/root,root-mirror/root,karies/root,root-mirror/root,root-mirror/root,karies/root,root-mirror/root,root-mirror/root,olifre/root,root-mirror/root,karies/root,karies/root,root-mirror/root,karies/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,karies/root,olifre/root,karies/root,karies/root,olifre/root,root-mirror/root,karies/root,root-mirror/root,karies/root