K 10
svn:author
V 3
mjg
K 8
svn:date
V 27
2019-05-08T16:30:38.252214Z
K 7
svn:log
V 450
Reduce umtx-related work on exec and exit

- there is no need to take the process lock to iterate the thread
  list after single-threading is enforced
- typically there are no mutexes to clean up (testable without taking
  the global umtx lock)
- typically there is no need to adjust the priority (testable without
  taking thread lock)

Reviewed by:	kib
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D20160

END