r245757 introduced warning output if update method is set to CVS_UPDATE
or SUP_UPDATE.

CVS exporter for head/ is turned off for nearly one month now.

It is finally time to swing the ax at these update methods.

Reviewed by:	eadler
MFC after:	1 month
Fix typo introduced in r251084.

MFC after:	1 month
X-MFC-With:	r251084
Remove references to CVS_UPDATE and SUP_UPDATE to catch up with r251084.

MFC after:	1 month
X-MFC-With:	r251084, r251085
Revert a local change that sets the default for UsePrivilegeSeparation to
"sandbox" instead of "yes".  In sandbox mode, the privsep child is unable
to load additional libraries and will therefore crash when trying to take
advantage of crypto offloading on CPUs that support it.