ICU-21776: tag icu @60c1857f96... for use in CLDR

ICU-21581 ICU Change Reports for 70rc

See unicode-org#1877

ICU-21581: tag icu @13fb584b96... for use in CLDR

ICU-21215 Add default constructor to FormattedNumberRange

ICU-21581: tag icu @e2fafa5840... for use in CLDR

ICU-21581: tag icu @4a6ad3dc93... for use in CLDR

ICU-21560 mingw: Remove version numbers from link flags

ICU-21480 Update double-conversion

ICU-21480: tag icu @c263b5b370ca6de3746338e8451acdb174619823 for use …

…in CLDR

ICU-21480: tag icu @7159e334ff12893b857de9a92e1c2eae4f3399fc for use …

…in CLDR