gopack: fixes for Plan 9 build
gopack: fixes for Plan 9 build

. removed an unnexessary initialisation.
. replaced 0 with 0L to match print format that in turn matched
  the type of the original function return value.

R=golang-dev
CC=golang-dev, rsc
http://codereview.appspot.com/5306072

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

h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang