wininet: Initialize user_len before GetUserNameW call.

Fixes a regression introduced by 441347f084.

Signed-off-by: Sebastian Lackner <sebastian@fds-team.de>
Signed-off-by: Jacek Caban<jacek@codeweavers.com>
Signed-off-by: Alexandre Julliard <julliard@winehq.org>

dlls/wininet/cookie.c

@@ -151,6 +151,7 @@ static WCHAR *create_cookie_url(substr_t domain, substr_t path, substr_t *ret_pa
 
     static const WCHAR cookie_prefix[] = {'C','o','o','k','i','e',':'};
 
+    user_len = sizeof(user)/sizeof(WCHAR);
     if(!GetUserNameW(user, &user_len))
         return FALSE;
     user_len--;