Documentation link only works for first symbol if multiple identical are present

[nagisa]

In case documentation page displays multiple symbols with the same name, only the first one can be linked to.

For example fmt on u32 page: http://doc.rust-lang.org/std/primitive.u32.html#method.fmt

[hinsley]

It's just a matter of giving each link a unique identifier. I'll get to work on it.

[l0kod]

Same for examples links.

[alexcrichton]

I'm going to close this in favor of #17476 as I think that's the best route to go (removing these anchors altogether and making them hyperlinks).