selinux-policy: Add test case for pam_timestamp_check + PAM module
    
    This TC should cover the pam_timestamp_check program and the
    pam_timestamp.so module which can be executed by unconfined
    and confined users. Necessary SELinux policy rules are tested.
    SELinux label on the directory, where _pam_timestamp_key file
    is located, is also tested.
    
    The TC can be parametrized. Description is in the PURPOSE file.