Back port of wxSocket-related fixes from trunk.

This patch combines the changes from the following trunk revisions:
 - r61675
 - r61676
 - r61677
 - r61678
 - r61685
 - r61686
 - r61687
 - r61688
 - r61689
 - r61690
 - r61696
 - r61726

It refactors wxSocketImpl creation to use a Mac-specific version of it in GUI
Mac applications which fixes generation of socket events under Mac (see #11030)
and also fixes bug in wxSocketServer::WaitForAccept() (see #11107).

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_2_9_0_BRANCH@61734 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/private/fdiohandler.h

@@ -0,0 +1,54 @@
+///////////////////////////////////////////////////////////////////////////////
+// Name:        wx/private/fdiohandler.h
+// Purpose:     declares wxFDIOHandler class
+// Author:      Vadim Zeitlin
+// Created:     2009-08-17
+// RCS-ID:      $Id: wxhead.h,v 1.11 2009-06-29 10:23:04 zeitlin Exp $
+// Copyright:   (c) 2009 Vadim Zeitlin <vadim@wxwidgets.org>
+// Licence:     wxWindows licence
+///////////////////////////////////////////////////////////////////////////////
+
+#ifndef _WX_PRIVATE_FDIOHANDLER_H_
+#define _WX_PRIVATE_FDIOHANDLER_H_
+
+// ----------------------------------------------------------------------------
+// wxFDIOHandler: interface used to process events on file descriptors
+// ----------------------------------------------------------------------------
+
+class wxFDIOHandler
+{
+public:
+    wxFDIOHandler() { m_regmask = 0; }
+
+    // called when descriptor is available for non-blocking read
+    virtual void OnReadWaiting() = 0;
+
+    // called when descriptor is available  for non-blocking write
+    virtual void OnWriteWaiting() = 0;
+
+    // called when there is exception on descriptor
+    virtual void OnExceptionWaiting() = 0;
+
+    // called to check if the handler is still valid, only used by
+    // wxSocketImplUnix currently
+    virtual bool IsOk() const { return true; }
+
+
+    // get/set the mask of events for which we're currently registered for:
+    // it's a combination of wxFDIO_{INPUT,OUTPUT,EXCEPTION}
+    int GetRegisteredEvents() const { return m_regmask; }
+    void SetRegisteredEvent(int flag) { m_regmask |= flag; }
+    void ClearRegisteredEvent(int flag) { m_regmask &= ~flag; }
+
+
+    // virtual dtor for the base class
+    virtual ~wxFDIOHandler() { }
+
+private:
+    int m_regmask;
+
+    wxDECLARE_NO_COPY_CLASS(wxFDIOHandler);
+};
+
+#endif // _WX_PRIVATE_FDIOHANDLER_H_
+