Revert "Userland: Invoke tzset in apps that care about time zones"

This reverts most of commit ede5c9548e.
The one change not reverted is ClockWidget.h, so that the taskbar clock
can continue to notice time zone changes.

Userland/Utilities/ddate.cpp

@@ -8,7 +8,6 @@
 #include <LibCore/DateTime.h>
 #include <LibCore/System.h>
 #include <LibMain/Main.h>
-#include <time.h>
 #include <unistd.h>
 
 class DiscordianDate {
@@ -105,8 +104,6 @@ ErrorOr<int> serenity_main(Main::Arguments)
 {
     TRY(Core::System::pledge("stdio rpath"));
 
-    tzset();
-
     auto date = Core::DateTime::now();
     outln("Today is {}", DiscordianDate(date).to_string());