MFC: 249514

MFC: 249514
Point args[0] not at the thread that is ending but at the one that
is starting.  This is in line with practice in OpenSolaris.

Note that this change is only in ULE and not in the 4BSD scheduler.
Once this change settles in (MFC timeout has expired) we'll try it out
on 4BSD as well.

PR:		177706
Submitted by:	Tiwei Bie

git-svn-id: svn://svn.freebsd.org/base/stable/9@252070 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f