Updated lwip.patch for Linux compatibility, CMakeLists.txt, and fixed other minor compile-time warnings

include/VirtualTap.h

@@ -30,11 +30,12 @@
  * Virtual Ethernet tap device
  */
 
-#ifndef ZT_VIRTUALTAP_HPP
-#define ZT_VIRTUALTAP_HPP
+#ifndef ZT_VIRTUALTAP_H
+#define ZT_VIRTUALTAP_H
 
+#ifndef _MSC_VER
 extern int errno;
-
+#endif
 
 #include "Mutex.hpp"
 #include "MulticastGroup.hpp"

include/lwipopts.h

@@ -39,16 +39,14 @@
 #ifndef __LWIPOPTS_H__
 #define __LWIPOPTS_H__
 
-//#define LWIP_SUPPORT_CUSTOM_PBUF 	0
-
 /*
  *  Provides its own errno
  */
 
 #if __ANDROID__
 #define LWIP_PROVIDE_ERRNO          0
-#else
-#define LWIP_PROVIDE_ERRNO          0
+#elif !defined(_MSC_VER)
+#define LWIP_PROVIDE_ERRNO          1
 #endif
 
 /*