godoc: hide link to blog in header in CN

Change-Id: I952ce003edecdd62179a8dfbc3c0e56f78eecfb1
Reviewed-on: https://go-review.googlesource.com/60071
Reviewed-by: Andrew Bonventre <andybons@golang.org>
Run-TryBot: Andrew Bonventre <andybons@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

godoc/static/godoc.html

@@ -32,7 +32,9 @@
 <a href="/pkg/">Packages</a>
 <a href="/project/">The Project</a>
 <a href="/help/">Help</a>
+{{if not .GoogleCN}}
 <a href="/blog/">Blog</a>
+{{end}}
 {{if .Playground}}
 <a id="playgroundButton" href="http://play.golang.org/" title="Show Go Playground">Play</a>
 {{end}}