[cpp-threads] Brief example ITANIUM Implementation for C/C++ MemoryModel

[Doug Lea]

Hans Boehm wrote:

>>
> The seq_cst operations must effectively ensure that data-race-free
> programs using only seq_cst operations behave sequentially consistently.

I wonder if a better naming scheme is available.
Probably some programmers will think along the lines:
   I'm using atomics to temporarily break sequential
   consistency. So if I want to get it back wrt this
   variable upon this load, I should use seq_cst mode.
Which is of course not what it does. But apparently Alexander
thought it should, and surely others will make the same
misinterpretation.

Maybe distinguish modes maintain_seq_cst vs establish_seq_cst?
Or some better names along those lines.

-Doug