fixes some (not all) buffer overreads during decoding pentax makernote entries. am: 836cfdb99e am: 0a45dca22e am: 24bdc1361a am: 8e051e1ef6

Original change: https://googleplex-android-review.googlesource.com/c/platform/external/libexif/+/12970376

Change-Id: I257b536b98945e3c13a2c985227d761ce99493a9