net: fix bugs in packStructValue
net: fix bugs in packStructValue

packStructValue was cutting off last byte of uint32
in _Dns_msg.Unpack, use packRR for rr types

R=rsc
CC=golang-dev
http://codereview.appspot.com/844048

Committer: Russ Cox <5ad239cb8a44f659eaaee0aa1ea5b94947abe557@golang.org>

gnanderson/go,bdwalton/debian-golang,gnanderson/go,pombredanne/go-deleteme,tianon/debian-golang,h8liu/golang,h8liu/golang,tv42/old-go,apparentlymart/golang,apparentlymart/golang,bdwalton/debian-golang,pombredanne/go-deleteme,apparentlymart/golang,bdwalton/debian-golang,tv42/old-go,pombredanne/go-deleteme,apparentlymart/golang,h8liu/golang,tianon/debian-golang,ssrl/go,pombredanne/go-deleteme,pombredanne/go-deleteme,pombredanne/go-deleteme,h8liu/golang,tianon/debian-golang,ssrl/go,dsriram/golang,tv42/old-go,ssrl/go,nightlyone/golang,h8liu/golang,bdwalton/debian-golang,apparentlymart/golang,nightlyone/golang,dsriram/golang,nightlyone/golang,h8liu/golang,dsriram/golang,nightlyone/golang,tianon/debian-golang,nightlyone/golang,bdwalton/debian-golang,ssrl/go,gnanderson/go,ssrl/go,bdwalton/debian-golang,nightlyone/golang,ssrl/go,bdwalton/debian-golang,h8liu/golang,dsriram/golang,tv42/old-go,apparentlymart/golang,tianon/debian-golang,dsriram/golang,gnanderson/go,tv42/old-go,gnanderson/go,nightlyone/golang,gnanderson/go,apparentlymart/golang,bdwalton/debian-golang,tv42/old-go,ssrl/go,tianon/debian-golang,pombredanne/go-deleteme,dsriram/golang,gnanderson/go,tianon/debian-golang,dsriram/golang,tianon/debian-golang,tv42/old-go