libexif: Avoid buffer overflow due to compiler optimization am: ba7f703b28 am: 62e2456a62 am: 9fb8525139

Original change: https://googleplex-android-review.googlesource.com/c/platform/external/libexif/+/12828416

Change-Id: I69c5fcc498d91a6afd2610b11c9e6a386845501d