socket-util: closesocket() for Windows.

For Windows sockets, one has to call closesocket() to
close the sockets.

Signed-off-by: Gurucharan Shetty <gshetty@nicira.com>
Acked-by: Ben Pfaff <blp@nicira.com>

lib/socket-util.c

@@ -810,7 +810,7 @@ exit:
             memset(ssp, 0, sizeof *ssp);
         }
         if (fd >= 0) {
-            close(fd);
+            closesocket(fd);
             fd = -1;
         }
     } else {
@@ -958,7 +958,7 @@ error:
     if (ssp) {
         memset(ssp, 0, sizeof *ssp);
     }
-    close(fd);
+    closesocket(fd);
     return -error;
 }