go spec: unsafe.Alignof/Offsetof/Sizeof return uintptr
go spec: unsafe.Alignof/Offsetof/Sizeof return uintptr

This is (indirectly) a language change. Per e-mail discussion
on golang-dev.

Fixes issue 1943.

R=rsc, iant, r, ken
CC=golang-dev
http://codereview.appspot.com/4581058

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