selinux: Disconnect before closing the handle
    
    libsemanage documentation says:
    ~~~~
    be sure that a semanage_disconnect() was previously called if the handle
    was connected.
    ~~~~
    
    Otherwise we get a memory leak.
    
    Reviewed-by: Michal Židek <mzidek@redhat.com>
    (cherry picked from commit aa00d67b2a8e07c9080e7798defdc6c774c93465)