don't remove/add back the socket to the list of inputs monitored by the event loop...

don't remove/add back the socket to the list of inputs monitored by the event loop all the time but just leave it there until the socket is destroyed; this should be beneficial from performance point of view (although hard to measure) and also makes the code simpler

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@57610 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775