Investigate performance of structured bindings, tie, and naive approach

[ryanelandt]

The naive approach to unpacking the latitude and longitude is:

  const auto lat1r_lon1r = GetLatLonRadians(src);
  const double lat1r = lat1r_lon1r.first;
  const double lon1r = lat1r_lon1r.second;

This solution is less compact than either:

const auto [lat1r, lon1r] = GetLatLonRadians(src);

or

tie(lat1r, lon1r) = GetLatLonRadians(src);

Investigate why.