Macro profile_wait

macro_rules! profile_wait {
    () => { ... };
    ($id:expr) => { ... };
    ($id:expr, $data:expr) => { ... };
}

Create a special profiling scope that indicates that we are waiting for some other thread to finish.

You should pass in the name of the thing you are waiting for as the first argument.

Example

let normals = {
    profile_wait!("compute_normals");
    things.par_iter().for_each(compute_normals)
};