Build fix for Win64 after r16521.

src/platform/socket.cc

Index: src/platform/socket.cc
diff --git a/src/platform/socket.cc b/src/platform/socket.cc
index e82c38c32c77c08ea46cc91a44717e865835124d..2fce6f2992d35955e9e11f0fe5f23e0c6147aaeb 100644
--- a/src/platform/socket.cc
+++ b/src/platform/socket.cc
@@ -128,7 +128,8 @@ bool Socket::Connect(const char* host, const char* port) {
   for (struct addrinfo* ai = info; ai != NULL; ai = ai->ai_next) {
     // Try to connect using this addr info.
     while (true) {
-      result = ::connect(native_handle_, ai->ai_addr, ai->ai_addrlen);
+      result = ::connect(
+          native_handle_, ai->ai_addr, static_cast<int>(ai->ai_addrlen));
       if (result == 0) {
         freeaddrinfo(info);
         return true;