Explicitly require Security Officer's approval for kernel PRNG bits.

Note that there is ongoing discussion about approval requirement
for userland PRNG bits.

Reviewed by:	so (des)
Approved by:	core (jhb)
Approved by:	re (gjb)

LOCKS

@@ -12,3 +12,7 @@ releng/5.*	Requires Security Officer approval.
 releng/6.*	Requires Security Officer approval.
 releng/7.*	Requires Security Officer approval.
 releng/8.*	Requires Security Officer approval.
+head/sys/dev/random			Requires Security Officer approval.
+head/sys/libkern/arc4random.c		Requires Security Officer approval.
+stable/*/sys/dev/random			Requires Security Officer approval.
+stable/*/sys/libkern/arc4random.c	Requires Security Officer approval.