rustdoc: hardcode each header as a link.

This avoids having to include JS in the guide/tutorial/manual pages just
to get the headers being links. The on-hover behaviour showing the
little section marker § is preserved, because that gives a useful hint
that the heading is a link.

src/librustdoc/html/static/main.js

@@ -600,10 +600,4 @@
 
     initSearch(searchIndex);
 
-    $.each($('h1, h2, h3'), function(idx, element) {
-        if ($(element).attr('id') != undefined) {
-            $(element).append('<a href="#' + $(element).attr('id') + '" ' +
-                              'class="anchor"> § </a>');
-        }
-    });
 }());