Adjust the bitmapButton size according the bitmap size when set bitmap to BitmapButton in wxUniv port

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@77782 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/univ/bmpbuttn.cpp

@@ -94,6 +94,7 @@ bool wxBitmapButton::ChangeBitmap(const wxBitmap& bmp)
         return false;
 
     m_bitmap = bitmap;
+    SetInitialSize(bitmap.GetSize());
 
     return true;
 }