Merge pull request #3681 from TobiSchluter/bugfix/dont_include_winsock2

Bugfix/dont include winsock2

RELICENSE/TobiSchluter.md

+# Permission to Relicense under MPLv2 or any other OSI approved license chosen by the current ZeroMQ BDFL
+
+This is a statement by Tobias Schlüter
+that grants permission to relicense its copyrights in the libzmq C++
+library (ZeroMQ) under the Mozilla Public License v2 (MPLv2) or any other 
+Open Source Initiative approved license chosen by the current ZeroMQ 
+BDFL (Benevolent Dictator for Life).
+
+A portion of the commits made by the Github handle "TobiSchluter", with
+commit author "TobiSchluter", are copyright of Tobias Schlüter .
+This document hereby grants the libzmq project team to relicense libzmq, 
+including all past, present and future contributions of the author listed above.
+
+Tobias Schlüter
+2019/09/13

include/zmq.h

@@ -71,7 +71,6 @@ extern "C" {
 #error You need at least Windows XP target
 #endif
 #endif
-#include <winsock2.h>
 #endif
 
 /*  Handle DSO symbol visibility                                             */
@@ -498,7 +497,12 @@ ZMQ_EXPORT int zmq_socket_monitor (void *s_, const char *addr_, int events_);
 /******************************************************************************/
 
 #if defined _WIN32
-typedef SOCKET zmq_fd_t;
+// Windows uses a pointer-sized unsigned integer to store the socket fd.
+#if defined _WIN64
+typedef unsigned __int64 zmq_fd_t;
+#else
+typedef unsigned int zmq_fd_t;
+#endif
 #else
 typedef int zmq_fd_t;
 #endif