Force umask to a controlled value for test runs.
Force umask to a controlled value for test runs.

BUG=chromium-os:35181
TEST=unittests on lucid/precise pass

Change-Id: I2f0761646a9f3ee89fa2d0bfc252a889f6724888
Reviewed-on: https://gerrit.chromium.org/gerrit/35163
Commit-Ready: Brian Harring <fdc2d0a2e2340b623587cee5ea8dff425d1eb1f3@chromium.org>
Tested-by: Brian Harring <fdc2d0a2e2340b623587cee5ea8dff425d1eb1f3@chromium.org>
Reviewed-by: David James <f231dc574bbeb62604660cbc162d1b8642a0a3af@chromium.org>

coreos/chromite,chadversary/chromiumos.chromite,coreos/chromite,zhang0137/chromite,bpsinc-native/src_third_party_chromite,chadversary/chromiumos.chromite,bpsinc-native/src_third_party_chromite,bpsinc-native/src_third_party_chromite,coreos/chromite,zhang0137/chromite,zhang0137/chromite