net: sort records returned by LookupMX
net: sort records returned by LookupMX

R=rog, adg, rsc
CC=golang-dev
http://codereview.appspot.com/4388048

Committer: Andrew Gerrand <395a7d33bec8475c9b83b7d440f141bcbd994aa5@golang.org>

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