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_5_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/b00e7555e58d8c6184ed61b65879fac7f291f318

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(-)