Log Message:
icu: Update to 68.1

Changelog:
Common Changes

    CLDR 38
        Support for units of measurement in inflected languages (phase 1)
        14 new measurement units: candela, imperial quart, etc.
        Improved locale ID canonicalization spec & data
        New language at Modern coverage: Norwegian Nynorsk
        New languages at Moderate coverage: Fulah (Adlam), Chakma, Asturian
        New languages at Basic coverage: Dogri, Sanskrit
    Measurement unit preferences (ICU-20568)
        New usage() option on NumberFormatter to select the most appropriate \ 
unit for a locale and context
        New outputUnit() getter on FormattedNumber to get the output unit after \ 
resolution
        In skeletons, specify the context using the "usage" stem
        Example: locale "en-GB", skeleton "usage/person \ 
unit-width-full-name unit/kilogram", input 80 (expressed in kilograms), \ 
output "12 stone, 8.4 pounds"
        Usages are pulled in from CLDR (e.g. CLDR v38 Unit Preferences).
    PluralRules selection for ranges of numbers (ICU-21190)
    Locale ID canonicalization now conforms to the CLDR spec including edge \ 
cases; co-developed with CLDR spec & data improvements (ICU-21236, ICU-21115 \ 
& others)
    New LocaleMatcher options: custom threshold (ICU-21144), no default locale \ 
(ICU-21029)
    DateIntervalFormat supports output options such as capitalization (ICU-20651)
    Uppercasing for the Armenian language (hy) now maps ligature to (ICU-13416)
    Data size reduction: Rule-based segmentation data files (RBBI) use a more \ 
compact data format and are now half as large (ICU-13565)
    Measurement units are normalized in skeleton string output: i.e., calling \ 
toSkeleton() on a NumberFormatter returns "unit/meter" instead of \ 
"measure-unit/length-meter"
    The ICU User Guide has been migrated to Markdown format, hosted via GitHub \ 
Pages: https://unicode-org.github.io/icu/userguide/
    Removed usage of terms like "blacklist" (ICU-21176), \ 
"master" (ICU-21242), and "grandfathered" (ICU-21184) as \ 
much as possible.
    Time zone data (tzdata) version 2020d (2020-oct-21)
    PluralRules category for compact notation numbers in French (ICU-13836)

ICU4C Specific Changes

    New C API for number range formatting (unicode/unumberrangeformatter.h), for \ 
example "750 m - 1.2 km" (ICU-21182)