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

ICU-21405 brs 68.2, update urename.h

ICU-21425 build: updates to maven/publication

- use SPDX license rather than raw license file
- minor srl update
- upload a full pom.xml instead of a generated one

ICU-21250 Update Apache Ant to 1.10.9

ICU-21250: tag ICU @766088ddb for ICU4J libs in CLDR

ICU-21249 integrate CLDR release-38-beta2 to ICU trunk

ICU-21249 Adds error code check to prevent segmentation fault if

See unicode-org#1356