do not require a running event loop, even under MSW, for the sockets to work: if...

do not require a running event loop, even under MSW, for the sockets to work: if the user code doesn't use events there is no reason for it to run the event loop, especially as it's not needed under the other platforms; instead use the same Select() implementation as under Unix under MSW too and, to avoid duplicating it, put it into the new GSocketBase class

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@56923 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775