test/mallocfin: relax test to 80% from 90%.
test/mallocfin: relax test to 80% from 90%.

R=r
CC=golang-dev
http://codereview.appspot.com/725042
abustany/go,abustany/go,abustany/go,abustany/go,abustany/go,abustany/go,abustany/go