[CFT] ASLR, PIE, and segvguard on 11-current and 10-stable

[Pedro Giffuni]

(Dropped the cross-posting, which *is* frowned upon)

While I do very much appreciate this work being done, and I agree we should have it in the tree, I would really prefer it opt-in rather opt-out, at least initially.

I know this may very well be the subject of a bikeshed of historical proportions but:

1) Understand this may break some applications (?).

2) It is yet undetermined what the performance effect will be.

I find it very neat that it can be enabled for jails though.

Pedro.