3849 implement __cxa_atexit/__cxa_finalize
Reviewed by: Hans Rosenfeld <hans.rosenfeld@nexenta.com>
Reviewed by: Robert Mustacchi <rm@joyent.com>
Approved by: Albert Lee <trisk@nexenta.com>
Merge branch 'master' of git://github.com/illumos/illumos-gate
S25 Fix xmod/libelf related build failures