Merge remote-tracking branch 'aosp/icu60' into aosp/master.

This upgrades AOSP to ICU 60.

Bug: 68208236
Test: ant check
Test: make check
Test: CtsIcuTestCases
Test: CtsLibcoreOjTestCases
Test: CtsLibcoreTestCases
Change-Id: If8a83ba2892a80edf7a36f71104daee48889c763