cmd/godoc: initialize filesystem and metadata for -url
cmd/godoc: initialize filesystem and metadata for -url

Unlike when using -http, godoc -url didn't initialize the "filesystem"
and metadata that are used when generating responses. This CL adds this
initialization, so that -url provides the same results as an HTTP
request when using -http.

Fixes issue 4335.

R=golang-dev, minux.ma
CC=golang-dev
http://codereview.appspot.com/6817075

Committer: Shenghou Ma <b563c57947dc20eb81988e3e3c22786764c14ca8@gmail.com>

apparentlymart/golang,apparentlymart/golang,pombredanne/go-deleteme,gnanderson/go,apparentlymart/golang,tv42/old-go,pombredanne/go-deleteme,apparentlymart/golang,tv42/old-go,gnanderson/go,gnanderson/go,gnanderson/go,tv42/old-go,tv42/old-go,dsriram/golang,dsriram/golang,tv42/old-go,pombredanne/go-deleteme,dsriram/golang,tv42/old-go,pombredanne/go-deleteme,tv42/old-go,dsriram/golang,gnanderson/go,apparentlymart/golang,pombredanne/go-deleteme,dsriram/golang,gnanderson/go,dsriram/golang,apparentlymart/golang,dsriram/golang,gnanderson/go,pombredanne/go-deleteme,apparentlymart/golang,pombredanne/go-deleteme