audit: add exclude filter extension to feature bitmap

Add to the audit feature bitmap to indicate availability of the
extension of the exclude filter to include PID, UID, AUID, GID, SUBJ_*.

RFE: add additional fields for use in audit filter exclude rules
https://github.com/linux-audit/audit-kernel/issues/5

Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>