pgsql: Update our mapping of Windows time zone names using CLDR info.

Update our mapping of Windows time zone names using CLDR info.

This corrects a bunch of entries in win32_tzmap[], and adds a few
new ones, based on the CLDR project's windowsZones.xml file.
Non-cosmetic changes fall into four main categories:

* Flat-out errors:

US/Aleutan doesn't exist
America/Salvador doesn't exist
Asia/Baku is wrong for Yerevan
Asia/Dhaka (Bangladesh) is wrong for Astana (Kazakhstan)
Europe/Bucharest is wrong for Chisinau
America/Mexico_City is wrong for Chetumal
America/Buenos_Aires is wrong for Cayenne
America/Caracas has its own zone, so poor fit for La Paz
US/Eastern is wrong for Haiti
US/Eastern is wrong for Indiana (East)
Asia/Karachi is wrong for Tashkent
Etc/UTC+12 doesn't exist
Signs of Etc/GMT zones were backwards

* Judgment calls:

(These changes follow CLDR's choices, except for the first one)

Use Europe/London for "Greenwich Standard Time", since that seems much
more likely than Africa/Casablanca to be what people will think that
zone name means. CLDR has Atlantic/Reykjavik here, but that's no better.

Asia/Shanghai seems a better fit than Hong Kong for "China Standard
Time".

Europe/Sarajevo is now a link to Belgrade, ie "Central Europe Standard
Time"; so use Warsaw for "Central European Standard Time".

America/Sao_Paulo seems more representative than Araguaina for
"E. South America Standard Time".

Africa/Johannesburg seems more representative than Harare for
"South Africa Standard Time".

* New Windows zone names:

"Israel Standard Time"
"Kaliningrad Standard Time"
"Russia Time Zone N" for various N
"Singapore Standard Time"
"South Sudan Standard Time"
"W. Central Africa Standard Time"
"West Bank Standard Time"
"Yukon Standard Time"

Some of these replace older spellings, but I kept the older spellings
too in case our code runs on a machine with the older data.

* Replace aliases (tzdb Links) with underlying city-named zones:

(This tracks tzdb's longstanding practice, and reduces inconsistency
with the rest of the entries, as well as with CLDR.)

US/Alaska
Asia/Kuwait
Asia/Muscat
Canada/Atlantic
Australia/Canberra
Canada/Saskatchewan
US/Central
US/Eastern
US/Hawaii
US/Mountain
Canada/Newfoundland
US/Pacific

Back-patch to all supported branches, as is our usual practice for
time zone data updates.

Discussion: https://postgr.es/m/3266414.1633045628@sss.pgh.pa.us

Branch
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REL9_6_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/dbec5a2fea4d5d6a52136dd169b0abe5b68fe1ec

Modified Files
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src/bin/initdb/findtimezone.c | 157 ++++++++++++++++++++++++++++--------------
1 file changed, 106 insertions(+), 51 deletions(-)