Reduce overlinking of libdtrace consumers with libctf, libelf, libproc.

The proper place for this list is _DP_dtrace.

Due to removing the LDADD_dtrace, more LIBADD are needed in
cddl/usr.sbin/dtrace to prevent underlinking.

This fixes overlinking in cddl/usr.sbin/lockstat and
cddl/usr.sbin/plockstat.

Sponsored by: EMC / Isilon Storage Division