hg: build-infra/jdk8: Oops uname -s not uname -a

[kelly.ohair at oracle.com]

Changeset: dec1dd0abf7f
Author:    ohair
Date:      2012-08-06 11:15 -0700
URL:       http://hg.openjdk.java.net/build-infra/jdk8/rev/dec1dd0abf7f

Oops   uname -s not uname -a

! common/bin/test_builds.sh