[Video] Warn when booting a bounding box game on an unsupported GPU

Source/Core/VideoCommon/MainBase.cpp

@@ -120,9 +120,6 @@ u32 VideoBackendBase::Video_GetQueryResult(PerfQueryType type)
 
 u16 VideoBackendBase::Video_GetBoundingBox(int index)
 {
-  if (!g_ActiveConfig.backend_info.bSupportsBBox)
-    return 0;
-
   if (!g_ActiveConfig.bBBoxEnable)
   {
     static bool warn_once = true;
@@ -133,6 +130,17 @@ u16 VideoBackendBase::Video_GetBoundingBox(int index)
     return 0;
   }
 
+  if (!g_ActiveConfig.backend_info.bSupportsBBox)
+  {
+    static bool warn_once = true;
+    if (warn_once)
+      PanicAlertT("This game requires bounding box emulation to run properly but your graphics "
+                  "card or its drivers do not support it. As a result you will experience bugs or "
+                  "freezes while running this game.");
+    warn_once = false;
+    return 0;
+  }
+
   Fifo::SyncGPU(Fifo::SyncGPUReason::BBox);
 
   AsyncRequests::Event e;