internal/netreflect: more use of internal/nettest package
internal/netreflect: more use of internal/nettest package

Change-Id: I4473e69bbb445ab27554f2dc625d0cbd79d7cfe5
Reviewed-on: https://go-review.googlesource.com/35072
Run-TryBot: Mikio Hara <e2f4d2eec1d9a1f781345cdd7260d7d52e6468ae@gmail.com>
TryBot-Result: Gobot Gobot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>
Reviewed-by: Matt Layher <76528ff2e917253aa2211f68e4ca60b5b846dcf5@gmail.com>

golang/net