Cherry-pick: ICU-21455 Add new API ubrk_clone() and deprecate ubrk_safeClone()

Upstream commit: https://github.com/unicode-org/icu/commit/048e46674aec9a0f90f40064011abadb9ac8ee04

Bug: 177225118
Test: m droid
Merged-In: I390582df719cb21f4b3718329fdeed7759f3c3bd
Change-Id: I390582df719cb21f4b3718329fdeed7759f3c3bd
(cherry picked from commit 95ef19646e8e28d2dd9171dc35cfeb85b908d645)
6 files changed