MFC r235459 and r235471

MFC r235459 and r235471

 r235459:
  Implement the DTrace sched provider.  This implementation aims to be
  compatible with the sched provider implemented by Solaris and its open-
  source derivatives.  Full documentation of the sched provider can be found
  on Oracle's DTrace wiki pages.

  Note that for compatibility with scripts originally written for Solaris,
  serveral probes are defined that will never fire.  These probes are defined
  to fire when Solaris-specific features perform certain actions.  As these
  features are not present in FreeBSD, the probes can never fire.

  Also, I have added a two probes that are not defined in Solaris, lend-pri
  and load-change.  These probes have been added to make it possible to
  collect schedgraph data with DTrace.

  Finally, a few probes are defined in Solaris to take a cpuinfo_t *
  argument.  As it was not immediately clear to me how to translate that to
  FreeBSD, currently those probes are passed NULL in place of a cpuinfo_t *.

  Sponsored by: Sandvine Incorporated

 r235471:
  Fix typo in function name SDT_PROBE4 and unbreak 4BSD UP.

git-svn-id: svn://svn.freebsd.org/base/stable/8@236345 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f