PATCH (libstdc++-v3 mainline): Re-enable i386/atomicity.h

[Loren James Rittle]

> Not to beat a dying or already dead horse but what is the final solution 
> for 3.3?

I am sorry if I failed to CC you since your name was on the committed
patch.  On the 3.3 branch (in libstdc++-v3/config/cpu), there is an
i386/atomicity.h file that contains the implementation that works on
all IA32 archs.  There is an i486/atomicity.h file that contains the
implementation that works on all i486 and above CPUs.  There are no
macro-keyed regions in either file.  There are no non-i386
instructions in __asm__ statements in i386/atomicity.h (unlike 3.2.X
and before).  Poeple that want i486 SMP locking instructions shall
configure their port triple to match i[4-]86-*-*.  There was no time
to develop a better patch to handle the requirements of both desktop
OS (rarely multilib'd on subtle CPU advancement) and embedded
(typically, heavily multilib'd according to you) users in a robust
manner given the time we learned of a better i386 atomic implementation.

Regards,
Loren