Create audit DISTRO_FEATURE to enable audit support into compilation. It is already introduced into systemd commit id 1bf5e676912c2cdf63b576796117135ef314580f . Few recipies make it dependent from selinux, but it should be independent features: ${@bb.utils.contains('DISTRO_FEATURES', 'selinux', 'selinux audit', '', d)} Let me know your opinion.
The DISTRO_FEATURES are for system-wide tuning or configuration. Are there recipes other than systemd and maybe auditd ? perf, dbus, shadow, cronie(sp?) pseudo, all have PACKAGECONFIGs for audit so it probably makese sense. Can you test and send a set of patches to oe-core and other lists ?
A nice idea but we need someone to work on it.