Add a hasUtcZone() for telephony tz detection

Telephony code currently contains a static list of countries
known to use UTC at some point in the year. This method will
be used instead. Not only does it use latest data but it can
check based on a time signal, making the response more
correct. This approach is probably more memory hungry than
the telephony code but it is only used under certain
circumstances.

If speed or memory usage becomes a problem it can be improved
by including hint data in tzlookup.xml to record whether a
country ever uses UTC, which can be statically generated and
make the check only iterate through zones for countries that
sometimes use UTC and avoid the expensive cases like US, RU,
CA, BR - countries that never use UTC and have a lot of zones.

Test: vogar luni/src/test/java/libcore/libcore/util/CountryTimeZonesTest.java
Bug: 37494871
Change-Id: I5a3b876ccc3f2915c2a5b69fe026e368102382c5

0 files changed, 0 insertions, 0 deletions