pgsql: Update time zone data files to tzdata release 2018c.

Update time zone data files to tzdata release 2018c.

DST law changes in Brazil, Sao Tome and Principe. Historical corrections
for Bolivia, Japan, and South Sudan. The "US/Pacific-New" zone has been
removed (it was only a link to America/Los_Angeles anyway).

Branch
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REL_10_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/2d71b2700b20f2a2274d69598c6fc979cba7f9b5

Modified Files
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src/timezone/data/tzdata.zi | 22 +++++++++++++---------
src/timezone/known_abbrevs.txt | 1 -
src/timezone/tznames/Africa.txt | 3 +--
3 files changed, 14 insertions(+), 12 deletions(-)