cmd/godoc: fix anchor links for constructors

Fixes golang/go#15866

Change-Id: I67f41026c64046ca581251fb0851d337d2651560
Reviewed-on: https://go-review.googlesource.com/23531
Reviewed-by: Andrew Gerrand <[email protected]>

Author: kostya-sh

godoc/static/package.html

@@ -200,7 +200,7 @@ <h2 id="{{$tname_html}}">type <a href="{{posLink_url $ .Decl}}">{{$tname_html}}<
 			{{range .Funcs}}
 				{{$name_html := html .Name}}
 				<h3 id="{{$name_html}}">func <a href="{{posLink_url $ .Decl}}">{{$name_html}}</a>
-					<a class="permalink" href="#{{$tname_html}}">&#xb6;</a>
+					<a class="permalink" href="#{{$name_html}}">&#xb6;</a>
 				</h3>
 				<pre>{{node_html $ .Decl true}}</pre>
 				{{comment_html .Doc}}