Merge r228057 from head to stable/9:

Merge r228057 from head to stable/9:

  Change the Makefile in cddl/lib/drti to use bsd.lib.mk instead of
  bsd.prog.mk -- we need to compile PIC, which requires a library build.
  With this change, USDT (userspace DTrace probes) work from within
  shared libraries.

  PR:             kern/159046
  Submitted by:   Alex Samorukov <samm at os2.kiev.ua>
  Comments by:    Scott Lystig Fritchie <slfritchie at snookles.com>

Approved by:	re (xxx)

git-svn-id: svn://svn.freebsd.org/base/stable/9@228073 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f