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/IXSocket.h

@@ -43,6 +43,7 @@ namespace ix
         // Functions to check whether there is activity on the socket
         PollResultType poll(int timeoutMs = kDefaultPollTimeout);
         bool wakeUpFromPoll(uint64_t wakeUpCode);
+        bool isWakeUpFromPollSupported();
 
         PollResultType isReadyToWrite(int timeoutMs);
         PollResultType isReadyToRead(int timeoutMs);
@@ -83,6 +84,9 @@ namespace ix
         std::atomic<int> _sockfd;
         std::mutex _socketMutex;
 
+        static bool readSelectInterruptRequest(const SelectInterruptPtr& selectInterrupt,
+                                               PollResultType* pollResult);
+
     private:
         static const int kDefaultPollTimeout;
         static const int kDefaultPollNoTimeout;