Moved all Win16 definitions out of the standard Windows headers.

diff --git a/include/winsock2.h b/include/winsock2.h
index 3129329..a473675 100644
--- a/include/winsock2.h
+++ b/include/winsock2.h
@@ -8,7 +8,6 @@
 #define __WINSOCK2API__
 
 #include "winsock.h"
-#include "wtypes.h"
 
 /* proper 4-byte packing */
 #include "pshpack4.h"
@@ -145,6 +144,10 @@
 #  define IFF_MULTICAST         0x00000010 /* multicast is supported */
 #endif
 
+#ifndef GUID_DEFINED
+#include "guiddef.h"
+#endif
+
 #define MAX_PROTOCOL_CHAIN 7
 #define BASE_PROTOCOL      1
 #define LAYERED_PROTOCOL   0