Update .gitignore
Update .gitignore

Add mkspecs/ include/ and lib/ to the ignore list

Change-Id: Ifad1eb78e3bd1b2b825a30a31df325e836c77e3e
Reviewed-by: Kurt Pattyn <da83d6ada5df79ff647b4271d0d788c6f1bafca2@gmail.com>

pixty/qtwebsockets,remimixlr/QtWebsocket,pixty/qtwebsockets,SfietKonstantin/qtwebsockets