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

(cherry picked from commit 175f02ed6f19b4912eb345448d38d54c6c61d6e9)
CB-6212 iOS: fix warnings compiled under arm64 64-bit

(cherry picked from commit 175f02ed6f19b4912eb345448d38d54c6c61d6e9)
RTC#55592 edit IBM-MODIFICATIONS file