rename the internal functions that do ml_foo ops on classes to hfsc_cl_foo.
rename the internal functions that do ml_foo ops on classes to hfsc_cl_foo.

this avoids confusion with the public functions (hfsc_enqueue,
hfsc_dequeue, etc), and maps almost 1:1 to the mbuf list ops they
now use.

ok mpi@ henning@ mikeb@

orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars