[$] Disabling SELinux's runtime disable

Distributors have been enabling the SELinux security module for nearly20 years now, and many administrators have been disabling it on theirsystems for almost as long. There are a few ways in which SELinux can bedisabled on any given system, including command-line options, a run-timeswitch, or simply not loading a policy after boot. One of those ways,however, is about to be disabled itself.