FullscreenUI: Fix compile with cheevos compile-time disabled

src/frontend-common/fullscreen_ui.cpp

@@ -1100,6 +1100,8 @@ static bool ToggleButtonForNonSetting(const char* title, const char* summary, co
   return true;
 }
 
+#ifdef WITH_CHEEVOS
+
 static void DrawAchievementsLoginWindow()
 {
   ImGui::SetNextWindowSize(LayoutScale(700.0f, 0.0f));
@@ -1185,6 +1187,8 @@ static bool ConfirmChallengeModeEnable()
   return true;
 }
 
+#endif
+
 static bool WantsToCloseMenu()
 {
   // Wait for the Close button to be released, THEN pressed