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/IXNetSystem.h

@@ -78,7 +78,7 @@ namespace ix
     bool initNetSystem();
     bool uninitNetSystem();
 
-    int poll(struct pollfd* fds, nfds_t nfds, int timeout);
+    int poll(struct pollfd* fds, nfds_t nfds, int timeout, void** event);
 
     const char* inet_ntop(int af, const void* src, char* dst, socklen_t size);
     int inet_pton(int af, const char* src, void* dst);