Do not return pointer to local from get_timezone

The pointed at variable was also a wchar_t array, not char, and so also
convert the contents to UTF-8. The static buffer is sized for the worst
case and the conversion will always succeed.

src/main.c

@@ -506,15 +506,15 @@ const char *get_timezone(const struct tm *local_time)
 {
 #ifdef _WIN32
     // Windows-specific code
+    static char namebuf[32*3];  // worst case for UTF-8
     TIME_ZONE_INFORMATION tz_info;
+    wchar_t *name = tz_info.StandardName;
     if (GetTimeZoneInformation(&tz_info) == TIME_ZONE_ID_DAYLIGHT && local_time->tm_isdst > 0)
     {
-        return tz_info.DaylightName; // DST time zone name
-    }
-    else
-    {
-        return tz_info.StandardName; // Standard time zone name
+        name = tz_info.DaylightName;
     }
+    WideCharToMultiByte(CP_UTF8, 0, name, -1, namebuf, sizeof(namebuf), NULL, NULL);
+    return namebuf;
 #else
     // Unix-like systems (Linux/macOS) code
     extern char *tzname[2]; // tzname[0] is standard, tzname[1] is DST