net/http: fix broken TestIssue4191_InfiniteGetToPutTimeout
net/http: fix broken TestIssue4191_InfiniteGetToPutTimeout

Test creates 2 tcp connections for put and get. Make sure
these are closed properly after test is over, otherwise
server hangs waiting for connection to be closed.

R=golang-dev, bradfitz, dave
CC=golang-dev
http://codereview.appspot.com/6842109
abustany/go,abustany/go,abustany/go,abustany/go,abustany/go,abustany/go,abustany/go