Fixed an issue where closing a cygtar file doesn't close the file handle.
Fixed an issue where closing a cygtar file doesn't close the file handle.

R=bradnelson@google.com, mseaborn@chromium.org
TEST= trybots

Review URL: https://codereview.chromium.org/222603002

git-svn-id: 721b910a23eff8a86f00c8fd261a7587cddf18f8@12978 fcba33aa-ac0c-11dd-b9e7-8d5594d729c2

sbc100/native_client,sbc100/native_client,sbc100/native_client,sbc100/native_client,sbc100/native_client,sbc100/native_client