o Introduce an 'options REGRESSION'-dependant sysctl namespaces,
'regression.*'.
o Add 'regression.securelevel_nonmonotonic', conditional on 'options
REGRESSION', which allows the securelevel to be lowered for the purposes of efficient regression testing of securelevel policy decisions. Regression tests for securelevels will be committed shortly.
NOTE: 'options REGRESSION' should never be used on production machines, as
it permits violation of system invariants so as to improve the ability to
effectively test edge cases, and improve testing efficiency.