Update ICU to 64-2-rc

- Support new Japanese Era (952305)
- Update to Unicode 12.1
- Fix undefined U_DISABLE_VERSION_SUFFIX warning (949962)
For more detail, see
http://site.icu-project.org/download/64

Also
- Fix Fuzzer bug of RegExp breakage (949885)


Bug: 952305, 949962, 949885, 952305
Change-Id: I32616f805c0d824b80786b502d96a13c201e15b3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/deps/icu/+/1566439
Reviewed-by: Jungshik Shin <jshin@chromium.org>
566 files changed