Fix for MINGW32 and clang on windows (#352) (#357)

* Update IXSocket.h

Avoid "conflicting declaration 'typedef SSIZE_T ssize_t'"

* Update IXUdpSocket.h

* Update IXNetSystem.cpp

ENOSPC and EAFNOSUPPORT are not defined for clang on windows

ixwebsocket/IXNetSystem.cpp

@@ -8,6 +8,12 @@
 #include <cstdint>
 #include <cstdio>
 #ifdef _WIN32
+#ifndef EAFNOSUPPORT
+  #define EAFNOSUPPORT 102
+#endif
+#ifndef ENOSPC
+  #define ENOSPC 28
+#endif
 #include <vector>
 #endif
 

ixwebsocket/IXSocket.h

@@ -14,8 +14,10 @@
 
 #ifdef _WIN32
 #include <basetsd.h>
+#ifdef _MSC_VER
 typedef SSIZE_T ssize_t;
 #endif
+#endif
 
 #include "IXCancellationRequest.h"
 #include "IXProgressCallback.h"

ixwebsocket/IXUdpSocket.h

@@ -12,8 +12,10 @@
 
 #ifdef _WIN32
 #include <basetsd.h>
+#ifdef _MSC_VER
 typedef SSIZE_T ssize_t;
 #endif
+#endif
 
 #include "IXNetSystem.h"