There doesn't seem to be a way to get Uncrustify to put commas at

the start of wrapped function call continuation lines, but at the
end of struct initializers/enums/etc lines.  I think the least bad
is commas at the end, especially now that it's got the happy
four-space indent for continuations.

I may play with this more later, but this seems to be good for now,
we'll see how it works out in actual use.