Adds MESHTASTIC_EXCLUDE_TZ option (#4423)

src/main.cpp

@@ -689,6 +689,7 @@ void setup()
     screen = new graphics::Screen(screen_found, screen_model, screen_geometry);
 
     // setup TZ prior to time actions.
+#if !MESHTASTIC_EXCLUDE_TZ
     if (*config.device.tzdef) {
         setenv("TZ", config.device.tzdef, 1);
     } else {
@@ -696,6 +697,7 @@ void setup()
     }
     tzset();
     LOG_DEBUG("Set Timezone to %s\n", getenv("TZ"));
+#endif
 
     readFromRTC(); // read the main CPU RTC at first (in case we can't get GPS time)