[cdjaqrac] comments in merged tzdata time zones

tzdata version 2021b controversially merged a lot of time zones that have agreed since 1970.  among other things, this caused comments in the database to become harder to understand.

as comparison, first, below are all the entries from the 2021a database (Debian Bullseye, before the change) that have both a comment and cover multiple countries (regions).  entries numbered 1, 2, and 3 have comments that are marginally confusing, not obvious which part of the comment refers to which country.

	Regions	Time Zone	Comment
1	AS:Samoa (American) UM:US minor outlying islands	Pacific/Pago_Pago	Samoa, Midway
2	US:United States UM:US minor outlying islands	Pacific/Honolulu	Hawaii
	NG:Nigeria AO:Angola BJ:Benin CD:Congo (Dem. Rep.) CF:Central African Rep. CG:Congo (Rep.) CM:Cameroon GA:Gabon GQ:Equatorial Guinea NE:Niger	Africa/Lagos	West Africa Time
	CH:Switzerland DE:Germany LI:Liechtenstein	Europe/Zurich	Swiss time
	MZ:Mozambique BI:Burundi BW:Botswana CD:Congo (Dem. Rep.) MW:Malawi RW:Rwanda ZM:Zambia ZW:Zimbabwe	Africa/Maputo	Central Africa Time
	RU:Russia UA:Ukraine	Europe/Simferopol	Crimea
3	RE:Réunion TF:French Southern & Antarctic Lands	Indian/Reunion	Réunion, Crozet, Scattered Islands
	TH:Thailand KH:Cambodia LA:Laos VN:Vietnam	Asia/Bangkok	Indochina (most areas)
	NZ:New Zealand AQ:Antarctica	Pacific/Auckland	New Zealand time

below are entries from the 2021e database filtered by the same criteria.  there are many more confusing entries (numbered).  for example, in #6, which country is "Syowa" part of?  what if multiple countries have a location named Syowa?

	Regions	Time Zone	Comment
1	AS:Samoa (American) UM:US minor outlying islands	Pacific/Pago_Pago	Samoa, Midway
2	US:United States UM:US minor outlying islands	Pacific/Honolulu	Hawaii
3	US:United States CA:Canada	America/Phoenix	MST - Arizona (except Navajo), Creston BC
4	PA:Panama CA:Canada KY:Cayman Islands	America/Panama	EST - Panama, Cayman, ON (Atikokan), NU (Coral H)
5	CA:Canada BS:Bahamas	America/Toronto	Eastern - ON, QC (most areas), Bahamas
	PR:Puerto Rico AG:Antigua & Barbuda CA:Canada AI:Anguilla AW:Aruba BL:St Barthelemy BQ:Caribbean NL CW:Curaçao DM:Dominica GD:Grenada GP:Guadeloupe KN:St Kitts & Nevis LC:St Lucia MF:St Martin (French) MS:Montserrat SX:St Maarten (Dutch) TT:Trinidad & Tobago VC:St Vincent VG:Virgin Islands (UK) VI:Virgin Islands (US)	America/Puerto_Rico	AST
	NG:Nigeria AO:Angola BJ:Benin CD:Congo (Dem. Rep.) CF:Central African Rep. CG:Congo (Rep.) CM:Cameroon GA:Gabon GQ:Equatorial Guinea NE:Niger	Africa/Lagos	West Africa Time
	CH:Switzerland DE:Germany LI:Liechtenstein	Europe/Zurich	Swiss time
	MZ:Mozambique BI:Burundi BW:Botswana CD:Congo (Dem. Rep.) MW:Malawi RW:Rwanda ZM:Zambia ZW:Zimbabwe	Africa/Maputo	Central Africa Time
	RU:Russia UA:Ukraine	Europe/Simferopol	Crimea
6	SA:Saudi Arabia AQ:Antarctica KW:Kuwait YE:Yemen	Asia/Riyadh	Arabia, Syowa
7	RE:Réunion TF:French Southern & Antarctic Lands	Indian/Reunion	Réunion, Crozet, Scattered Islands
	TH:Thailand KH:Cambodia LA:Laos VN:Vietnam	Asia/Bangkok	Indochina (most areas)
	SG:Singapore MY:Malaysia	Asia/Singapore	Singapore, peninsular Malaysia
8	PG:Papua New Guinea AQ:Antarctica	Pacific/Port_Moresby	Papua New Guinea (most areas), Dumont d'Urville
	NZ:New Zealand AQ:Antarctica	Pacific/Auckland	New Zealand time

a stopgap fix: comments in zone1970.tab should be applicable only to the first country (the country that the city is in), or to all countries listed for that time zone.  for comments that apply only to some countries, move the comment to a Link time zone in zone.tab .  but god help you if that comment requires an accented character, not supported by the older zone.tab .  better, probably requiring software changes, is for zone1970.tab to also support Link time zones as entries with their own comments and coordinates.

incidentally, zone1970.tab says "Comments; present if and only if a country has multiple timezones", which is (arguably) violated by these merged entries.  for example, Panama has only one time zone, so its entry should not have a comment, but it does (#4).