go.tools/godoc: reverse reversed redirects
go.tools/godoc: reverse reversed redirects

Make godoc work again for go spec and memory model doc.

TBR=rsc
CC=golang-dev
https://codereview.appspot.com/14368043

tmc/mirror-go.tools,t-yuki/go.tools.old,tmc/mirror-go.tools,t-yuki/go.tools.old,tmc/mirror-go.tools,t-yuki/go.tools.old