Use only wxFont ctor from wxFontInfo in the samples

Follow the documentation advice and prefer to use the ctor taking
wxFontInfo as it makes the code slightly shorter and more readable.

samples/exec/exec.cpp

@@ -522,8 +522,7 @@ MyFrame::MyFrame(const wxString& title, const wxPoint& pos, const wxSize& size)
 
     // create the listbox in which we will show misc messages as they come
     m_lbox = new wxListBox(this, wxID_ANY);
-    wxFont font(12, wxFONTFAMILY_TELETYPE, wxFONTSTYLE_NORMAL,
-                wxFONTWEIGHT_NORMAL);
+    wxFont font(wxFontInfo(12).Family(wxFONTFAMILY_TELETYPE));
     if ( font.IsOk() )
         m_lbox->SetFont(font);