message: fixed if-then end label jump
diff: @@ -150,7 +150,7 @@ function emitBril(prog: ts.Node, checker: ts.TypeChecker): bril.Program {
  // Statement chunks.
  builder.buildLabel(thenLab);
  emit(if_.thenStatement);
  - builder.buildEffect("jmp", ["endif"]);
  + builder.buildEffect("jmp", [endLab]);
  builder.buildLabel(elseLab);
  if (if_.elseStatement) {
  emit(if_.elseStatement);
  