fix MSVC2015 type convert (#70)

fix MSVC2015 C2664 error.

Author: wanggao1990

trantor/net/InetAddress.cc

@@ -189,11 +189,19 @@ std::string InetAddress::toIp() const
     char buf[64];
     if (addr_.sin_family == AF_INET)
     {
+#if defined _MSC_VER && _MSC_VER == 1900
+        ::inet_ntop(AF_INET, (PVOID)&addr_.sin_addr, buf, sizeof(buf));
+#else
         ::inet_ntop(AF_INET, &addr_.sin_addr, buf, sizeof(buf));
+#endif
     }
     else if (addr_.sin_family == AF_INET6)
     {
+#if defined _MSC_VER && _MSC_VER == 1900
+        ::inet_ntop(AF_INET6, (PVOID)&addr6_.sin6_addr, buf, sizeof(buf));
+#else
         ::inet_ntop(AF_INET6, &addr6_.sin6_addr, buf, sizeof(buf));
+#endif
     }
 
     return buf;