K 10
svn:author
V 3
mjg
K 8
svn:date
V 27
2019-05-12T06:32:46.634545Z
K 7
svn:log
V 407
random(4): depessimize arc4random

- __predict_false reseeding on entry as it is almost never true.
- don't blindly atomic_cmpset as on x86 it ends up dirtying the cacheline.
it almost ever succeeds per above
- fetch the timestamp prior to getting the cpu number

Reviewed by:	cem
Approved by:	secteam (delphij)
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D20242

END