Fix more harmless warnings.

Fix a warning about unused parameters and another about signed/unsigned
comparison during samples and tests compilation.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@63873 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

samples/stc/edit.cpp

@@ -190,7 +190,7 @@ void Edit::OnEditClear (wxCommandEvent &WXUNUSED(event)) {
     Clear ();
 }
 
-void Edit::OnKey  (wxStyledTextEvent &event)
+void Edit::OnKey (wxStyledTextEvent &WXUNUSED(event))
 {
     wxMessageBox("OnKey");
 }