avoid ly_tzset_once in ly_time_time2str

It does not seem necessary to call ly_tzset_once() from
ly_time_time2str().
If the user changes TZ env variable, they must explicitly call tzset()
as well.

Author: irfanHaslanded

src/tree_data_common.c

@@ -1620,30 +1620,12 @@ ly_time_tz_offset(void)
     return ly_time_tz_offset_at(time(NULL));
 }
 
-/**
- * @brief Call tzset() if not already called by this process.
- */
-static void
-ly_tzset_once(void)
-{
-    static int ly_tzset_called = 0;
-
-    if (ly_tzset_called) {
-        return;
-    }
-    tzset();
-    ly_tzset_called = 1;
-}
-
 LIBYANG_API_DEF int
 ly_time_tz_offset_at(time_t time)
 {
     struct tm tm_local, tm_utc;
     int result = 0;
 
-    /* init timezone */
-    ly_tzset_once();
-
     /* get local and UTC time */
     localtime_r(&time, &tm_local);
     gmtime_r(&time, &tm_utc);
@@ -1791,9 +1773,6 @@ ly_time_time2str(time_t time, const char *fractions_s, char **str)
 
     LY_CHECK_ARG_RET(NULL, str, LY_EINVAL);
 
-    /* init timezone */
-    ly_tzset_once();
-
     /* convert */
     if (!localtime_r(&time, &tm)) {
         return LY_ESYS;