bits/atomic.h atomic*_t types

[Roland McGrath]

AFAIK the atomic*_t types have not been used for anything yet.  There are
no comments on the definitions (bad), so I am guessing what they are for.
Are they intended to be like int_fastNN_t, i.e. a type that is at least
that large and can be accessed atomically?  (The existing uses of atomic.h
assume that int and word/pointer size are usable atomically rather than
using these types, which is probably safe.)

All the bits/atomic.h files have copied the verbatim definitions from the
original i386 file.  All 4 sizes can be accessed with atomic instructions
on i386.  But I believe that on almost all other machines, only one or two
sizes (32 and/or 64 bits) really work.  So the definitions should be
changed for most machines, no?


Thanks,
Roland