audit: add syscall information to FEATURE_CHANGE records

Tie syscall information to FEATURE_CHANGE calls since it is a result of
user action.

See: https://github.com/linux-audit/audit-kernel/issues/80



Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
[PM: 80-char fixes]
Signed-off-by: Paul Moore <paul@paul-moore.com>