Win wsa select event (#342)

* Fix #323: Missing SelectInterrupt implementation for Windows

Using WSAEventSelect, WSAWaitForMultipleEvents and WSAEnumNetworkEvents to emulate poll() with an interrupt-event.

* Cleanup

* Fixed incomplete comment.

* Switched ifdefs to support other Unixes with pipe file descriptors

* Fixed: SelectInterrupt fallback code for getFd()==-1 && getEvent()==nullptr converted a PollResultType::Timeout into a ReadyForRead causing the HttpClient to fail because it uses a hard-coded "SelectInterrupt" instance that doesn't implement getFd() and getEvent().

* Fixed gcc compile errors

* - HttpClient now uses the SelectInterruptFactory
- Fixed wrong ix::poll result when using Windows WSA functions

* We must deselect the networkevents from the socket event. Otherwise the socket will report states that aren't there.

ixwebsocket/IXSelectInterrupt.h

@@ -24,6 +24,7 @@ namespace ix
         virtual bool clear();
         virtual uint64_t read();
         virtual int getFd() const;
+        virtual void* getEvent() const;
 
         // Used as special codes for pipe communication
         static const uint64_t kSendRequest;