[client] spice: check and track the primary surface format & validity

client/src/main.h

@@ -81,6 +81,7 @@ struct AppState
   uint8_t spiceUUID[16];
   bool    spiceReady;
   bool    initialSpiceDisplay;
+  bool    spicePrimarySurfaceValid;
   uint8_t guestUUID[16];
   bool    guestUUIDValid;
   KVMFROS guestOS;