Libport.cassert: enforce, enforce_eq are aver, aver_eq that cannot be disabled.
Libport.cassert: enforce, enforce_eq are aver, aver_eq that cannot be disabled.

See issue #4817.

	* include/libport/cassert (enforce, enforce_eq, ...): New.
	(aver, aver_eq, ...): Use them.

aldebaran/libport,aldebaran/libport,aldebaran/libport,aldebaran/libport,aldebaran/libport