resurrect architecture-specific atomic types to do a maximally portable atomic64 on i386.  we will tune it to use cmpxchg8b where available but until then...
resurrect architecture-specific atomic types to do a maximally portable atomic64 on i386.  we will tune it to use cmpxchg8b where available but until then...

git-svn-id: f2acecaac6fbd5a03f3d4799db58dda434111981@10029 3eda493b-6a19-0410-b2e0-ec8ea4dd8fda

pscedu/slash2-stable,pscedu/slash2-stable,pscedu/slash2-stable,pscedu/pfl,pscedu/pfl,pscedu/slash2-stable,pscedu/slash2-stable,pscedu/pfl,pscedu/slash2-stable,pscedu/pfl,pscedu/slash2-stable