Currently adding back in the SMR versions of freelist, queue (unbounded, many, many) and stack.

An observation by a colleague regarding IA64 made me realised that the IA64 instruction which compares one word but swaps two is enough for the data structures which require contious double-word compare-and-swap. You simply compare the counter. I’ll be making the necessary changes to support this. It is unfortunate this comes after IA64 has basically died!