Make ticky work, at least partly, on 64-bit machines
The ticky StgEntCounter structure was trying to be clever by using a fixed-width 32-bit field for the registeredp value. But the code generators are not up to handling structures packed tightly like this (on a 64-bit architecture); result seg-fault on 64-bit. Really there should be some complaint from the code generators, not simply a seg fault. Anyway I switched to using native words for StgEntCounter fields, and now at least it works.