Make () actually size 0
For `for` loop bodies, translate the type of the closure
based on the expr_loop_body expression and not the inner closure
Fix long lines in for loop trans change
One more place where for loops and their bodies need to be unconfused.
Correct (I hope) amd64 ABI handling for empty structs
Make empty structs debug-printable
Make vectors (& old ports) of zero-size types allocate one byte each.