MDEV-19243 Fix timezone handling on Windows to report standard timezone names

sql/gen_win_tzname_data.ps1

+# Generates a header file for converting between Windows timezone names to tzdb names
+# using CLDR data.
+# Usage: powershell -File gen_win_tzname_data.ps1 >  win_tzname_data.h
+
+write-output  "/* This file  was generated using gen_win_tzname_data.ps1 */"
+$xdoc = new-object System.Xml.XmlDocument
+$xdoc.load("https://unicode.org/repos/cldr/trunk/common/supplemental/windowsZones.xml")
+$nodes = $xdoc.SelectNodes("//mapZone[@territory='001']") # use default territory (001)
+foreach ($node in $nodes) {
+  write-output ('{L"'+ $node.other + '","'+ $node.type+'"},')
+}

sql/mysqld.cc

@@ -4009,6 +4009,39 @@ static int init_early_variables()
   return 0;
 }
 
+#ifdef _WIN32
+static void get_win_tzname(char* buf, size_t size)
+{
+  static struct
+  {
+    const wchar_t* windows_name;
+    const char*  tzdb_name;
+  }
+  tz_data[] =
+  {
+#include "win_tzname_data.h"
+    {0,0}
+  };
+  DYNAMIC_TIME_ZONE_INFORMATION  tzinfo;
+  if (GetDynamicTimeZoneInformation(&tzinfo) == TIME_ZONE_ID_UNKNOWN)
+  {
+    strncpy(buf, "unknown", size);
+    return;
+  }
+
+  for (size_t i= 0; tz_data[i].windows_name; i++)
+  {
+    if (wcscmp(tzinfo.TimeZoneKeyName, tz_data[i].windows_name) == 0)
+    {
+      strncpy(buf, tz_data[i].tzdb_name, size);
+      return;
+    }
+  }
+  wcstombs(buf, tzinfo.TimeZoneKeyName, size);
+  buf[size-1]= 0;
+  return;
+}
+#endif
 
 static int init_common_variables()
 {
@@ -4053,23 +4086,13 @@ static int init_common_variables()
 
   if (ignore_db_dirs_init())
     return 1;
-
-#ifdef HAVE_TZNAME
+#ifdef _WIN32
+  get_win_tzname(system_time_zone, sizeof(system_time_zone));
+#elif defined(HAVE_TZNAME)
   struct tm tm_tmp;
   localtime_r(&server_start_time,&tm_tmp);
   const char *tz_name=  tzname[tm_tmp.tm_isdst != 0 ? 1 : 0];
-#ifdef _WIN32
-  /*
-    Time zone name may be localized and contain non-ASCII characters,
-    Convert from ANSI encoding to UTF8.
-  */
-  wchar_t wtz_name[sizeof(system_time_zone)];
-  mbstowcs(wtz_name, tz_name, sizeof(system_time_zone)-1);
-  WideCharToMultiByte(CP_UTF8,0, wtz_name, -1, system_time_zone, 
-    sizeof(system_time_zone) - 1, NULL, NULL);
-#else
   strmake_buf(system_time_zone, tz_name);
-#endif /* _WIN32 */
 #endif /* HAVE_TZNAME */
 
   /*

sql/win_tzname_data.h

+/* This file  was generated using gen_win_tzname_data.ps1 */
+{L"Dateline Standard Time","Etc/GMT+12"},
+{L"UTC-11","Etc/GMT+11"},
+{L"Aleutian Standard Time","America/Adak"},
+{L"Hawaiian Standard Time","Pacific/Honolulu"},
+{L"Marquesas Standard Time","Pacific/Marquesas"},
+{L"Alaskan Standard Time","America/Anchorage"},
+{L"UTC-09","Etc/GMT+9"},
+{L"Pacific Standard Time (Mexico)","America/Tijuana"},
+{L"UTC-08","Etc/GMT+8"},
+{L"Pacific Standard Time","America/Los_Angeles"},
+{L"US Mountain Standard Time","America/Phoenix"},
+{L"Mountain Standard Time (Mexico)","America/Chihuahua"},
+{L"Mountain Standard Time","America/Denver"},
+{L"Central America Standard Time","America/Guatemala"},
+{L"Central Standard Time","America/Chicago"},
+{L"Easter Island Standard Time","Pacific/Easter"},
+{L"Central Standard Time (Mexico)","America/Mexico_City"},
+{L"Canada Central Standard Time","America/Regina"},
+{L"SA Pacific Standard Time","America/Bogota"},
+{L"Eastern Standard Time (Mexico)","America/Cancun"},
+{L"Eastern Standard Time","America/New_York"},
+{L"Haiti Standard Time","America/Port-au-Prince"},
+{L"Cuba Standard Time","America/Havana"},
+{L"US Eastern Standard Time","America/Indianapolis"},
+{L"Paraguay Standard Time","America/Asuncion"},
+{L"Atlantic Standard Time","America/Halifax"},
+{L"Venezuela Standard Time","America/Caracas"},
+{L"Central Brazilian Standard Time","America/Cuiaba"},
+{L"SA Western Standard Time","America/La_Paz"},
+{L"Pacific SA Standard Time","America/Santiago"},
+{L"Turks And Caicos Standard Time","America/Grand_Turk"},
+{L"Newfoundland Standard Time","America/St_Johns"},
+{L"Tocantins Standard Time","America/Araguaina"},
+{L"E. South America Standard Time","America/Sao_Paulo"},
+{L"SA Eastern Standard Time","America/Cayenne"},
+{L"Argentina Standard Time","America/Buenos_Aires"},
+{L"Greenland Standard Time","America/Godthab"},
+{L"Montevideo Standard Time","America/Montevideo"},
+{L"Magallanes Standard Time","America/Punta_Arenas"},
+{L"Saint Pierre Standard Time","America/Miquelon"},
+{L"Bahia Standard Time","America/Bahia"},
+{L"UTC-02","Etc/GMT+2"},
+{L"Azores Standard Time","Atlantic/Azores"},
+{L"Cape Verde Standard Time","Atlantic/Cape_Verde"},
+{L"UTC","Etc/GMT"},
+{L"GMT Standard Time","Europe/London"},
+{L"Greenwich Standard Time","Atlantic/Reykjavik"},
+{L"W. Europe Standard Time","Europe/Berlin"},
+{L"Central Europe Standard Time","Europe/Budapest"},
+{L"Romance Standard Time","Europe/Paris"},
+{L"Morocco Standard Time","Africa/Casablanca"},
+{L"Sao Tome Standard Time","Africa/Sao_Tome"},
+{L"Central European Standard Time","Europe/Warsaw"},
+{L"W. Central Africa Standard Time","Africa/Lagos"},
+{L"Jordan Standard Time","Asia/Amman"},
+{L"GTB Standard Time","Europe/Bucharest"},
+{L"Middle East Standard Time","Asia/Beirut"},
+{L"Egypt Standard Time","Africa/Cairo"},
+{L"E. Europe Standard Time","Europe/Chisinau"},
+{L"Syria Standard Time","Asia/Damascus"},
+{L"West Bank Standard Time","Asia/Hebron"},
+{L"South Africa Standard Time","Africa/Johannesburg"},
+{L"FLE Standard Time","Europe/Kiev"},
+{L"Israel Standard Time","Asia/Jerusalem"},
+{L"Kaliningrad Standard Time","Europe/Kaliningrad"},
+{L"Sudan Standard Time","Africa/Khartoum"},
+{L"Libya Standard Time","Africa/Tripoli"},
+{L"Namibia Standard Time","Africa/Windhoek"},
+{L"Arabic Standard Time","Asia/Baghdad"},
+{L"Turkey Standard Time","Europe/Istanbul"},
+{L"Arab Standard Time","Asia/Riyadh"},
+{L"Belarus Standard Time","Europe/Minsk"},
+{L"Russian Standard Time","Europe/Moscow"},
+{L"E. Africa Standard Time","Africa/Nairobi"},
+{L"Iran Standard Time","Asia/Tehran"},
+{L"Arabian Standard Time","Asia/Dubai"},
+{L"Astrakhan Standard Time","Europe/Astrakhan"},
+{L"Azerbaijan Standard Time","Asia/Baku"},
+{L"Russia Time Zone 3","Europe/Samara"},
+{L"Mauritius Standard Time","Indian/Mauritius"},
+{L"Saratov Standard Time","Europe/Saratov"},
+{L"Georgian Standard Time","Asia/Tbilisi"},
+{L"Caucasus Standard Time","Asia/Yerevan"},
+{L"Afghanistan Standard Time","Asia/Kabul"},
+{L"West Asia Standard Time","Asia/Tashkent"},
+{L"Ekaterinburg Standard Time","Asia/Yekaterinburg"},
+{L"Pakistan Standard Time","Asia/Karachi"},
+{L"India Standard Time","Asia/Calcutta"},
+{L"Sri Lanka Standard Time","Asia/Colombo"},
+{L"Nepal Standard Time","Asia/Katmandu"},
+{L"Central Asia Standard Time","Asia/Almaty"},
+{L"Bangladesh Standard Time","Asia/Dhaka"},
+{L"Omsk Standard Time","Asia/Omsk"},
+{L"Myanmar Standard Time","Asia/Rangoon"},
+{L"SE Asia Standard Time","Asia/Bangkok"},
+{L"Altai Standard Time","Asia/Barnaul"},
+{L"W. Mongolia Standard Time","Asia/Hovd"},
+{L"North Asia Standard Time","Asia/Krasnoyarsk"},
+{L"N. Central Asia Standard Time","Asia/Novosibirsk"},
+{L"Tomsk Standard Time","Asia/Tomsk"},
+{L"China Standard Time","Asia/Shanghai"},
+{L"North Asia East Standard Time","Asia/Irkutsk"},
+{L"Singapore Standard Time","Asia/Singapore"},
+{L"W. Australia Standard Time","Australia/Perth"},
+{L"Taipei Standard Time","Asia/Taipei"},
+{L"Ulaanbaatar Standard Time","Asia/Ulaanbaatar"},
+{L"Aus Central W. Standard Time","Australia/Eucla"},
+{L"Transbaikal Standard Time","Asia/Chita"},
+{L"Tokyo Standard Time","Asia/Tokyo"},
+{L"North Korea Standard Time","Asia/Pyongyang"},
+{L"Korea Standard Time","Asia/Seoul"},
+{L"Yakutsk Standard Time","Asia/Yakutsk"},
+{L"Cen. Australia Standard Time","Australia/Adelaide"},
+{L"AUS Central Standard Time","Australia/Darwin"},
+{L"E. Australia Standard Time","Australia/Brisbane"},
+{L"AUS Eastern Standard Time","Australia/Sydney"},
+{L"West Pacific Standard Time","Pacific/Port_Moresby"},
+{L"Tasmania Standard Time","Australia/Hobart"},
+{L"Vladivostok Standard Time","Asia/Vladivostok"},
+{L"Lord Howe Standard Time","Australia/Lord_Howe"},
+{L"Bougainville Standard Time","Pacific/Bougainville"},
+{L"Russia Time Zone 10","Asia/Srednekolymsk"},
+{L"Magadan Standard Time","Asia/Magadan"},
+{L"Norfolk Standard Time","Pacific/Norfolk"},
+{L"Sakhalin Standard Time","Asia/Sakhalin"},
+{L"Central Pacific Standard Time","Pacific/Guadalcanal"},
+{L"Russia Time Zone 11","Asia/Kamchatka"},
+{L"New Zealand Standard Time","Pacific/Auckland"},
+{L"UTC+12","Etc/GMT-12"},
+{L"Fiji Standard Time","Pacific/Fiji"},
+{L"Chatham Islands Standard Time","Pacific/Chatham"},
+{L"UTC+13","Etc/GMT-13"},
+{L"Tonga Standard Time","Pacific/Tongatapu"},
+{L"Samoa Standard Time","Pacific/Apia"},
+{L"Line Islands Standard Time","Pacific/Kiritimati"},