zip_archive: reject files that don't start with an LFH signature. am: dbacd826a1 am: 368ec42fa8 am: 6dbd1db1cf am: 58c10b2ab9  -s ours am: 2dbba44e2d
am: 583a11b339

Change-Id: I215d12f87d5d644f6ded52a59173d4d7f5940d07