6l: fix another "set and not used".
6l: fix another "set and not used".

R=rsc
CC=golang-dev
http://codereview.appspot.com/4433042

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