Delitmus parameter numbers are not correct

[MattWindsor91]

The delitmus parameter numbers are a total ordering on all parameters across all threads, and not across individual ones. This is benign usually, but becomes a problem if we're trying to handle parameter passing conventions such as aarch64's. The parameter numbers should represent the exact position in the parameter list.

[MattWindsor91]

I think I've fixed this now, though I'm using a heuristic that might go wrong if litmus tests are inconsistent with regards to parameter ordering across threads.