add minimal winsock->BSD networking header shims

also add license header to existing shims

include/win32netcompat.h

@@ -0,0 +1,22 @@
+#ifndef LIBCRYPTOCOMPAT_WIN32NETCOMPAT_H
+#define LIBCRYPTOCOMPAT_WIN32NETCOMPAT_H
+
+#ifdef _WIN32
+
+#include <ws2tcpip.h>
+
+#ifndef SHUT_RDWR
+#define SHUT_RDWR SD_BOTH
+#endif
+
+#ifndef SHUT_RD
+#define SHUT_RD SD_RECEIVE
+#endif
+
+#ifndef SHUT_WR
+#define SHUT_WR SD_SEND
+#endif
+
+#endif
+
+#endif