Don't log error messages when using the clipboard

wxClipboard::GetData()and wxClipboard::SetData() both log a "wxLogSysError" error-level message (see for example:  https://github.com/wxWidgets/wxWidgets/blob/v3.1.4/src/msw/clipbrd.cpp#L703 ). This logged message gets displayed as a messagebox to the user.

The logging can be disabled temporarily by creating a wxLogNull object. See https://docs.wxwidgets.org/3.0/classwx_log_null.html

Fixes https://gitlab.com/kicad/code/kicad/-/issues/6956

bitmap2component/bitmap2cmp_gui.cpp

@@ -683,6 +683,8 @@ void BM2CMP_FRAME::OnExportToClipboard( wxCommandEvent& event )
     std::string buffer;
     ExportToBuffer( buffer, format );
 
+    wxLogNull doNotLog; // disable logging of failed clipboard actions
+
     // Write buffer to the clipboard
     if (wxTheClipboard->Open())
     {