Expose ubrk_clone() from NDK - part 2

tools/icu4c_srcgen/libicu_export.txt is the only manual change,
and other file changes are generated by the script
tools/icu4c_srcgen/generate_ndk.py

CTS of ubrk_clone() should be covered in CtsIcu4cTestCases.
The test is TestBreakIteratorClone() located at
icu4c/source/test/cintltst/cbiapts.c

Bug: 177225118
Test: atest CtsIcu4cTestCases
Change-Id: I71f2eb80d99dc446a105d8733a791b85fb360898
5 files changed