CB-6212 iOS: fix warnings compiled under arm64 64-bit

(cherry picked from commit 007630da4866d867321008c6b8e1ebf57f05f259)
CB-6212 iOS: fix warnings compiled under arm64 64-bit

-fix one more warning

(cherry picked from commit db9fa24cf8ba165aabae0460a9cbeb1dd1d67e62)
RTC#55592 edit IBM-MODIFICATIONS file