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/IXWebSocketTransport.cpp

@@ -297,13 +297,11 @@ namespace ix
             lastingTimeoutDelayInMs = (1000 * _pingIntervalSecs) - timeSinceLastPingMs;
         }
 
-#ifdef _WIN32
-        // Windows does not have select interrupt capabilities, so wait with a small timeout
-        if (lastingTimeoutDelayInMs <= 0)
+        // The platform may not have select interrupt capabilities, so wait with a small timeout
+        if (lastingTimeoutDelayInMs <= 0 && !_socket->isWakeUpFromPollSupported())
         {
             lastingTimeoutDelayInMs = 20;
         }
-#endif
 
         // If we are requesting a cancellation, pass in a positive and small timeout
         // to never poll forever without a timeout.