message: Add a Tracer function to declare something as not needing tracing
  Summary: Useful to be explicit and check assumptions.
diff: @@ -799,6 +799,14 @@ impl<'v> Tracer<'v> {
  *value = self.adjust(*value)
  }
  + /// Helper function to annotate that this field has been considered for tracing,
  + /// but is not relevant because it has a static lifetime containing no relevant values.
  + /// Does nothing.
  + pub fn trace_static<T: 'static>(&self, value: &mut T) {
  + // Nothing to do because T can't contain the lifetime 'v
  + let _ = value;
  + }
  +
  pub(crate) fn reserve<'a, 'v2: 'v + 'a, T: AValue<'v2, ExtraElem = ()>>(
  &'a self,
  ) -> (Value<'v>, Reservation<'a, 'v2, T>) {
  