Xcode: Use ad-hoc signing during compiler id on macOS
Xcode 14 no longer accepts an empty signing identity for macOS. However, Xcode in general does not accept an ad-hoc signing identity for iOS. Switch based on the target platform.
Suppress an incidental warning in the "Run Script" build phase. Teach the RunCMake infrastructure to ignore some new warnings from xcodebuild.
Fixes: #23609 (closed)
Backport: release
Edited by Brad King