Fix integer overflow in FindEntry. am: 88d1cbf3b6 am: 0e19648bc9 am: a8f554a6b1

Original change: https://android-review.googlesource.com/c/platform/system/libziparchive/+/1580906

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: I13fb5244c4818f042651ef0e7d0005d47dbe6abe