Make wxDumpWindow() public and available in wxMSW too

This function was defined in wxGTK and wxOSX, but not in wxMSW or the
other ports, but it can be useful there too, so make it public and
define it in common code.

src/gtk/window.cpp

@@ -309,26 +309,6 @@ static wxPoint gs_lastGesturePoint;
 // the trace mask used for the focus debugging messages
 #define TRACE_FOCUS wxT("focus")
 
-#if wxUSE_LOG_TRACE
-// Function used to dump a brief description of a window.
-static
-wxString wxDumpWindow(wxWindowGTK* win)
-{
-    if ( !win )
-        return "(no window)";
-
-    wxString s = wxString::Format("%s(%p",
-                                  win->GetClassInfo()->GetClassName(), win);
-
-    wxString label = win->GetLabel();
-    if ( !label.empty() )
-        s += wxString::Format(", \"%s\"", label);
-    s += ")";
-
-    return s;
-}
-#endif // wxUSE_LOG_TRACE
-
 // A handy function to run from under gdb to show information about the given
 // GtkWidget. Right now it only shows its type, we could enhance it to show
 // more information later but this is already pretty useful.