http: increase header line limit, let req.Host override req.URL.Host
http: increase header line limit, let req.Host override req.URL.Host

Fixes issue 566.

R=rsc
CC=golang-dev
http://codereview.appspot.com/194074

Committer: Russ Cox <5ad239cb8a44f659eaaee0aa1ea5b94947abe557@golang.org>
abustany/go,abustany/go,abustany/go,abustany/go,abustany/go,abustany/go,abustany/go