Merge r261796 from head:

Merge r261796 from head:
  While it isn't too late and kvm_read_zpcpu() function isn't yet used
  outside libkvm(3), change its order of arguments, so that it is the
  same as in kvm_read().
Merge r261805 from head:
  Add kvm_getncpus() to obtain mp_ncpus.

git-svn-id: svn://svn.freebsd.org/base/stable/10@262740 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f