Core/Misc: Remove unsafe not thread-safe localtime() calls

Replace not thread-safe localtime() calls with thread-safe localtime_r().

(cherry picked from commit 5b08387792dae0afbf91ab74808dc978bf418bca)

src/server/scripts/Commands/cs_guild.cpp

@@ -278,7 +278,8 @@ public:
         // Format creation date
         char createdDateStr[20];
         time_t createdDate = guild->GetCreatedDate();
-        strftime(createdDateStr, 20, "%Y-%m-%d %H:%M:%S", localtime(&createdDate));
+        tm localTm;
+        strftime(createdDateStr, 20, "%Y-%m-%d %H:%M:%S", localtime_r(&createdDate, &localTm));
 
         handler->PSendSysMessage(LANG_GUILD_INFO_CREATION_DATE, createdDateStr); // Creation Date
         handler->PSendSysMessage(LANG_GUILD_INFO_MEMBER_COUNT, guild->GetMemberCount()); // Number of Members