LinuxKPI: Additions to rcu list.

• Add rcu list functions.
• Make rcu hlist's foreach macro use rcu calls instead of the non-rcu macro.
• Bump FreeBSD version so we have a checkpoint for the vboxvideo drm driver.

Reviewed by: hps
Approved by: imp (mentor), hps
MFC after: 1 week
Differential Revision: D20719