libc: add goos, goarch, goroot.  fixes build
libc: add goos, goarch, goroot.  fixes build

TBR=r
CC=golang-dev
http://codereview.appspot.com/190059

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