add wxImage::SetType() and use it in animation decoders (#9639)

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@54932 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/common/anidecod.cpp

@@ -304,6 +304,7 @@ bool wxANIDecoder::Load( wxInputStream& stream )
             if (!sm_handler.DoLoadFile(&image, stream, false /* verbose */, -1))
                 return false;
 
+            image.SetType(wxBITMAP_TYPE_ANI);
             m_images.Add(image);
         }
         else