ip_utils: replace #warning and define IN6_IS_ADDR_UNSPECIFIED

- Adds #pragma message to replace #warning directive

- Defines _WIN32_WINNT to windows 10 (0x0A00) which allows
  IN6_IS_ADDR_UNSPECIFIED to be defined in ws2tcpip.h

Change-Id: Id2406815830f24bbed744cbaca98dbd4fbcf515d
Tuleap: #790

src/ip_utils.cpp

@@ -247,7 +247,11 @@ ip_utils::getLocalNameservers()
 {
     std::vector<IpAddr> res;
 #if defined __ANDROID__ || defined _WIN32 || TARGET_OS_IPHONE
+#ifdef _MSC_VER
+#pragma message (__FILE__ "(" STR2(__LINE__) ") : -NOTE- " "Not implemented")
+#else
 #warning "Not implemented"
+#endif
 #else
     if (not (_res.options & RES_INIT))
         res_init();

src/ip_utils.h

@@ -32,6 +32,7 @@ extern "C" {
 #include <ciso646> // fix windows compiler bug
 
 #ifdef _WIN32
+    #define _WIN32_WINNT 0x0A00
     #include <ws2tcpip.h>
 
     //define in mingw