core: add support of specifier %@ for UTC time in function util_strftimeval

doc/en/weechat_plugin_api.en.adoc

@@ -4803,7 +4803,7 @@ This function is not available in scripting API.
 
 ==== util_strftimeval
 
-_WeeChat ≥ 4.2.0, updated in 4.3.0._
+_WeeChat ≥ 4.2.0, updated in 4.3.0, 4.7.0._
 
 Format date and time like function `strftime` in C library, using `struct timeval`
 as input, and supporting extra specifiers.
@@ -4820,6 +4820,8 @@ Arguments:
 * _string_: buffer where the formatted string is stored
 * _max_: string size
 * _format_: format, the same as _strftime_ function, with these extra specifiers:
+** `%@`: return the date expressed in Coordinated Universal Time (UTC)
+   instead of date relative to the user's specified timezone _(WeeChat ≥ 4.7.0)_
 ** `%.N` where `N` is between 1 and 6: zero-padded microseconds on N digits
    (for example `%.3` for milliseconds)
 ** `%f`: alias of `%.6`
@@ -4836,8 +4838,8 @@ C example:
 char time[256];
 struct timeval tv;
 gettimeofday (&tv, NULL);
-weechat_util_strftimeval (time, sizeof (time), "%FT%T.%f", &tv);
-/* result: 2023-12-26T18:10:04.460509 */
+weechat_util_strftimeval (time, sizeof (time), "%@%FT%T.%fZ", &tv);
+/* result: 2023-12-26T18:10:04.460509Z */
 ----
 
 [NOTE]

doc/fr/weechat_plugin_api.fr.adoc

@@ -4882,7 +4882,7 @@ Cette fonction n'est pas disponible dans l'API script.
 
 ==== util_strftimeval
 
-_WeeChat ≥ 4.2.0, mis à jour dans la 4.3.0._
+_WeeChat ≥ 4.2.0, mis à jour dans la 4.3.0, 4.7.0._
 
 Formatter la date et l'heure comme la fonction `strftime` de la bibliothèque C,
 en utilisant un `struct timeval` en entrée et en supportant des caractères de
@@ -4901,6 +4901,8 @@ Paramètres :
 * _max_ : taille de la chaîne
 * _format_ : format, le même que celui de la fonction _strftime_, avec des
   caractères de conversion supplémentaires :
+** `%@` : retourner la date exprimée en Temps Universel Coordonné (UTC)
+   au lieu de la date relative au fuseau horaire de l'utilisateur _(WeeChat ≥ 4.7.0)_
 ** `%.N` où `N` est entre 1 and 6: microsecondes remplies avec des zéros sur
    N chiffres (par exemple `%.3` pour les millisecondes)
 ** `%f` : alias de `%.6`
@@ -4917,8 +4919,8 @@ Exemple en C :
 char time[256];
 struct timeval tv;
 gettimeofday (&tv, NULL);
-weechat_util_strftimeval (time, sizeof (time), "%FT%T.%f", &tv);
-/* résultat : 2023-12-26T18:10:04.460509 */
+weechat_util_strftimeval (time, sizeof (time), "%@%FT%T.%fZ", &tv);
+/* résultat : 2023-12-26T18:10:04.460509Z */
 ----
 
 [NOTE]

doc/it/weechat_plugin_api.it.adoc

@@ -5023,7 +5023,7 @@ Questa funzione non è disponibile nelle API per lo scripting.
 // TRANSLATION MISSING
 ==== util_strftimeval
 
-_WeeChat ≥ 4.2.0, updated in 4.3.0._
+_WeeChat ≥ 4.2.0, updated in 4.3.0, 4.7.0._
 
 Format date and time like function `strftime` in C library, using `struct timeval`
 as input, and supporting extra specifiers.
@@ -5040,6 +5040,8 @@ Arguments:
 * _string_: buffer where the formatted string is stored
 * _max_: string size
 * _format_: format, the same as _strftime_ function, with these extra specifiers:
+** `%@`: return the date expressed in Coordinated Universal Time (UTC)
+   instead of date relative to the user's specified timezone _(WeeChat ≥ 4.7.0)_
 ** `%.N` where `N` is between 1 and 6: zero-padded microseconds on N digits
    (for example `%.3` for milliseconds)
 ** `%f`: alias of `%.6`
@@ -5056,8 +5058,8 @@ C example:
 char time[256];
 struct timeval tv;
 gettimeofday (&tv, NULL);
-weechat_util_strftimeval (time, sizeof (time), "%FT%T.%f", &tv);
-/* result: 2023-12-26T18:10:04.460509 */
+weechat_util_strftimeval (time, sizeof (time), "%@%FT%T.%fZ", &tv);
+/* result: 2023-12-26T18:10:04.460509Z */
 ----
 
 [NOTE]

doc/ja/weechat_plugin_api.ja.adoc

@@ -4937,7 +4937,7 @@ weechat_printf (NULL, "date: %s",
 // TRANSLATION MISSING
 ==== util_strftimeval
 
-_WeeChat ≥ 4.2.0, updated in 4.3.0._
+_WeeChat ≥ 4.2.0, updated in 4.3.0, 4.7.0._
 
 Format date and time like function `strftime` in C library, using `struct timeval`
 as input, and supporting extra specifiers.
@@ -4954,6 +4954,8 @@ Arguments:
 * _string_: buffer where the formatted string is stored
 * _max_: string size
 * _format_: format, the same as _strftime_ function, with these extra specifiers:
+** `%@`: return the date expressed in Coordinated Universal Time (UTC)
+   instead of date relative to the user's specified timezone _(WeeChat ≥ 4.7.0)_
 ** `%.N` where `N` is between 1 and 6: zero-padded microseconds on N digits
    (for example `%.3` for milliseconds)
 ** `%f`: alias of `%.6`
@@ -4970,8 +4972,8 @@ C example:
 char time[256];
 struct timeval tv;
 gettimeofday (&tv, NULL);
-weechat_util_strftimeval (time, sizeof (time), "%FT%T.%f", &tv);
-/* result: 2023-12-26T18:10:04.460509 */
+weechat_util_strftimeval (time, sizeof (time), "%@%FT%T.%fZ", &tv);
+/* result: 2023-12-26T18:10:04.460509Z */
 ----
 
 [NOTE]

doc/sr/weechat_plugin_api.sr.adoc

@@ -4663,7 +4663,7 @@ weechat_printf (NULL, "date: %s",
 
 ==== util_strftimeval
 
-_WeeChat ≥ 4.2.0, ажурирано у 4.3.0._
+_WeeChat ≥ 4.2.0, ажурирано у 4.3.0, 4.7.0._
 
 Форматира датум и време као функција `strftime` из C библиотеке, користећи `struct timeval`
 као улаз уз подршку за додатне спецификаторе.
@@ -4680,6 +4680,9 @@ int weechat_util_strftimeval (char *string, int max, const char *format, struct
 * _string_: бафер у који се смешта форматирани стринг
 * _max_: величина стринга
 * _format_: формат, исто као за _strftime_ функцију, са следећим додатним спецификаторима:
+// TRANSLATION MISSING
+** `%@`: return the date expressed in Coordinated Universal Time (UTC)
+   instead of date relative to the user's specified timezone _(WeeChat ≥ 4.7.0)_
 ** `%.N` где је `N` између 1 и 6: микросекунде допуњене нулама на N цифара
    (на пример `%.3` за милисекунде)
 ** `%f`: алијас за `%.6`
@@ -4696,8 +4699,8 @@ C пример:
 char time[256];
 struct timeval tv;
 gettimeofday (&tv, NULL);
-weechat_util_strftimeval (time, sizeof (time), "%FT%T.%f", &tv);
-/* резултат: 2023-12-26T18:10:04.460509 */
+weechat_util_strftimeval (time, sizeof (time), "%@%FT%T.%fZ", &tv);
+/* резултат: 2023-12-26T18:10:04.460509Z */
 ----
 
 [NOTE]