[cpp-threads] N2052 sequencing revisions & examples (moderatelylong)

[Peter Dimov]

I'd like the example

fetchadd_acquire( &x, 1 );
load_relaxed( &y ); // 0

//

fetchadd_acquire( &y, 1 );
load_relaxed( &x ); // 0

to be added and analyzed, if possible. If it doesn't permit the non-SC (0,0) 
outcome, _acquire would (probably) be much heavier than typically needed.