Provide LLVM pass names.

Just a little hint for debugging.
No-op: move NFAState[Hash] declaration.

Move the declaration and definition of NFAState and NFAStateHash closer to DFABuilder, which uses them, and which is closer to where they used to be.
Trivial: drop unused Manifest.size() method.

We used to need this when we queried the manifest for automata by ID; now that we use proper identifiers it is no longer the case.