fix: wrong timezone in android calendar

The tzname and tznamedst in timezone blob confuses some android
devices, so that they fallback to Greenwich Mean Time timezone
even though the other data in timezone blob contains the correct
information of the selected timezone (e.g. Central European
Standard Time). Setting tzname and tznamedst to empty strings
mitigates this issue.

Author: gromandreas

lib/utils/timezoneutil.php

@@ -1275,7 +1275,7 @@ private static function encodeTZName($name) {
 	 */
 	public static function GetSyncBlobFromTZ($tz) {
 		// set the correct TZ name (done using the Bias)
-		if (!isset($tz["tzname"]) || !$tz["tzname"] || !isset($tz["tznamedst"]) || !$tz["tznamedst"]) {
+		if (!isset($tz["tzname"]) || !isset($tz["tznamedst"])) {
 			$tz = TimezoneUtil::FillTZNames($tz);
 		}
 
@@ -1452,11 +1452,10 @@ public static function CreateTimezoneDefinitionObject($tzdef) {
 	 * @return array
 	 */
 	public static function GetTzFromTimezoneDef($tzdef) {
-		$tz = [];
-		// convert timezone name because in zcore the chars are nul-padded
-		if (!empty($tzdef['keyname'])) {
-			$tz['tzname'] = $tz['tznamedst'] = self::getMSTZnameFromTZName(iconv('UTF-16', 'UTF-8', $tzdef['keyname']));
-		}
+		$tz = [
+			'tzname' => '',
+			'tznamedst' => '',
+		];
 
 		foreach ($tzdef['rules'] as $rule) {
 			if ($rule['tzruleflags'] & TZRULE_FLAG_EFFECTIVE_TZREG) {