timezone: upgrade 2019c -> 2020a

See full changelog https://github.com/eggert/tz/blob/master/NEWS#L11



(From OE-Core rev: 9d74b048)

Signed-off-by: Pierre-Jean Texier <pjtexier@koncepto.io>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Anuj Mittal <anuj.mittal@intel.com>