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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REL9_4_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/fa86a32f9b3a8f44c118510cf21db6efea3a1d51

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(-)