Leave whitespace for logically grouped comments alone

Is seems that rustfmt is identifies an ending | (or perhaps simply not ;) as a continued block and doesn't mess with the whitespace, but it will change the formatting of the last entry:

Before

fn reduced_example(scaler: usize) {
    let control = (1 << 16) |     // Clock enable
                  (scaler << 8) | // Set PSEL to based on period
                  (1 << 7)  |     // Flash calibration done (set to default)
                  (1 << 1)  |     // Disable after reset
                  (1 << 0);       // Enable
}

After

fn reduced_example(scaler: usize) {
    let control = (1 << 16) |     // Clock enable
                  (scaler << 8) | // Set PSEL to based on period
                  (1 << 7)  |     // Flash calibration done (set to default)
                  (1 << 1)  |     // Disable after reset
                  (1 << 0); // Enable
}

I believe this is a similar but distinct case from #1275

No source file or test is named. Start by reproducing the Before/After Rust example and trace rustfmt's handling of continued | expressions with comments; done means the final comment retains the surrounding alignment instead of being reformatted independently.