pgsql: Suppress "Factory" zone in pg_timezone_names view for tzdata >=

Suppress "Factory" zone in pg_timezone_names view for tzdata >= 2016g.

IANA got rid of the really silly "abbreviation" and replaced it with one
that's only moderately silly.  But it's still pointless, so keep on not
showing it.

Branch
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REL9_6_STABLE

Details
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http://git.postgresql.org/pg/commitdiff/1b145a700158ab48c387d38f4830136d307a0e87

Modified Files
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src/backend/utils/adt/datetime.c | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)