Fix do while continue stmt

[lucic71]

A continue statement inside a do while breakes the iteration and re-evaluates the condition.

Our previous translation, i.e.

loop {
  ...
  if !cond {
    break
  }
}

never re-evaluated the condition after a continue, resulting in an infinite loop.

To fix this, use while instead of loop. This ensures that the condition is re-evaluated right after the continue:

let mut __do_while = true;
while __do_while || cond {
  __do_while = false;
  ...
}

__do_while makes sure that the first iteration of the loop is always executed.