libexif: Avoid buffer overflow due to compiler optimization am: 4c18b0fabf am: 3cbbf8c711 am: 2ac0cac132 am: e419bb6679

Original change: https://googleplex-android-review.googlesource.com/c/platform/external/libexif/+/12298339

Change-Id: Iaa76a9dafebc1436c879184b4f999b27ba90d446