KS2010: Security

Yeah, moving some uncontroversial (it would seem) bits of the grsecurity patch into mainline can both increase mainline security a bit and reduce a bit the size / ease a bit the maintenance of the grsecurity patch against a moving mainline.

For proper credit attribution, it requires coordination with the grsecurity people. Which I probably won't have time to do until next week, so feel free to beat me :)