[8u] RFR 8254982: (tz) Upgrade time-zone data to tzdata2020c

[Guo, James]

Hi,

Original bug:
  https://bugs.openjdk.java.net/browse/JDK-8254982
  https://git.openjdk.java.net/jdk/commit/55a0cad8

Although the original patch applies cleanly to 8u, yet the original patch doesn’t include
updates of tzdata under test/sun/util/calendar/zi/tzdata/, which are removed after 11u.

8u webrev:
http://cr.openjdk.java.net/~cverghese/webrevs/8254982-jdk8u/

Testing: x86_64 build, affected tests, tier1

Thanks,
-James