[cpp-threads] modes, interlude

[Peter Dimov]

Doug Lea wrote:

> If we are going to do this, is there any reason not go all the way and
> have four flavors of explicit barrier functions in the atomic classes
> and not bother adding modes to load, store etc?

Labels are less restrictive.

load.none
load.acq
other ops

allows the first load to migrate down below the other ops.

load.none
load.none
#loadload | #loadstore
other ops

does not.