policycoreutils: add option to build audit2allow

policycoreutils: add option to build audit2allow

This python utility scans the logs for messages logged when the system
denied permission for operations, and  generates  a snippet of policy
rules which, if loaded into policy, might have allowed  those operations
to succeed.  However, this utility only generates Type Enforcement (TE)
allow rules.

Signed-off-by: Adam Duskett <Adamduskett@outlook.com>
Reviewed-by: Matt Weber <matthew.weber@rockwellcollins.com>
[Thomas: adjust Config.in to propagate the dependencies of sepolgen,
checkpolicy and python3.]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>