Upgrade to ICU 64-2 from 64-2-rc

Also fix Abrt in icu_64::RegexCompile::handleCloseParen

Upstream PR and bug in ICU
https://unicode-org.atlassian.net/browse/ICU-20391
https://github.com/unicode-org/icu/pull/628

Bug: chromium:952851
Change-Id: I74540026171591c582747742c85abaf35b7edc0c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/deps/icu/+/1573807
Reviewed-by: Jungshik Shin <jshin@chromium.org>
48 files changed