libstrat: enable -Wextra, -Werror

This caught an embarrassingly large number of bugs.

libraries/libstratosphere/source/htc/server/driver/htc_htclow_driver.cpp

@@ -36,6 +36,7 @@ namespace ams::htc::server::driver {
 
     void HtclowDriver::SetDisconnectionEmulationEnabled(bool en) {
         /* NOTE: Nintendo ignores the input, here. */
+        AMS_UNUSED(en);
         m_disconnection_emulation_enabled = false;
     }