test/garbage: do not try to parse package bignum, which is gone.
test/garbage: do not try to parse package bignum, which is gone.

Fixes issue 1023.

R=gri
CC=golang-dev
http://codereview.appspot.com/1968043

tav/go,tav/go,tav/go,tav/go,tav/go,tav/go,tav/go