win32: fix variable use before initialization

Signed-off-by: NBlue Swirl <blauwirbel@gmail.com>

net/tap-win32.c

@@ -687,11 +687,11 @@ static int tap_win32_init(VLANState *vlan, const char *model,
 
     nc = qemu_new_net_client(&net_tap_win32_info, vlan, NULL, model, name);
 
+    s = DO_UPCAST(TAPState, nc, nc);
+
     snprintf(s->nc.info_str, sizeof(s->nc.info_str),
              "tap: ifname=%s", ifname);
 
-    s = DO_UPCAST(TAPState, nc, nc);
-
     s->handle = handle;
 
     qemu_add_wait_object(s->handle->tap_semaphore, tap_win32_send, s);