ICU-23338 Handle permanent DST metazone entries

Author: robertbastian

tools/cldr/cldr-to-icu/src/main/resources/ldml2icu_supplemental.txt

@@ -326,7 +326,11 @@
 //supplementalData/metaZones/metazoneInfo/timezone[@type="(%W)"]/usesMetazone[@from="(%A)"][@mzone="(%W)"][@stdOffset="(%A)"][@dstOffset="(%A)"] ; /metazoneInfo/"$1"/<$2> ; values=$3 "$2" "9999-12-31 23:59"
 //supplementalData/metaZones/metazoneInfo/timezone[@type="(%W)"]/usesMetazone[@from="(%A)"][@to="(%A)"][@mzone="(%W)"][@stdOffset="(%A)"][@dstOffset="(%A)"] ; /metazoneInfo/"$1"/<$2> ; values=$4 "$2" "$3"
 //supplementalData/metaZones/metazoneInfo/timezone[@type="(%W)"]/usesMetazone[@to="(%A)"][@mzone="(%W)"][@stdOffset="(%A)"][@dstOffset="(%A)"] ; /metazoneInfo/"$1"/<1970-01-01 00:00> ; values=$3 "1970-01-01 00:00" "$2"
-#
+# Ignore entries with just dstOffset completely. ICU does not currently support permanent-DST metazone membership (ICU4X does, which is why such entries exist).
+# //supplementalData/metaZones/metazoneInfo/timezone[@type="(%W)"]/usesMetazone[@from="(%A)"][@mzone="(%W)"][@dstOffset="(%A)"] ; /metazoneInfo/"$1"/<$2> ; values=$3 "$2" "9999-12-31 23:59"
+# //supplementalData/metaZones/metazoneInfo/timezone[@type="(%W)"]/usesMetazone[@from="(%A)"][@to="(%A)"][@mzone="(%W)"][@dstOffset="(%A)"] ; /metazoneInfo/"$1"/<$2> ; values=$4 "$2" "$3"
+# //supplementalData/metaZones/metazoneInfo/timezone[@type="(%W)"]/usesMetazone[@to="(%A)"][@mzone="(%W)"][@dstOffset="(%A)"] ; /metazoneInfo/"$1"/<1970-01-01 00:00> ; values=$3 "1970-01-01 00:00" "$2"
+
 //supplementalData/metaZones/metazoneIds/metazoneId[@shortId="(%A)"][@longId="(%A)"][@deprecated="false"] ; /metazoneIds/$1 ; values=$2
 
 //supplementalData/primaryZones/primaryZone[@iso3166="(%W)"] ; /primaryZones/$1 ; values={value}