Comments with /*********... are handled strangely

[huonw]

E.g. in extra::arc there is

/****************************************************************************
 * Immutable Arc
 ****************************************************************************/

/// An atomically reference counted wrapper for shared immutable state.
pub struct Arc<T> { priv x: UnsafeArc<T> }

which results in this HTML:

<hr>
<ul>
<li>Immutable Arc *************************************************************************** An atomically reference counted wrapper for shared immutable state.</li>
</ul>

(Appearing here at time of filing.)

[alexcrichton]

I think that in general doc-comment stripping needs to be more robust.

I believe that solving this issue would also solve #9417