MFC 228361:

MFC 228361:
Explicitly use curthread while manipulating td_fpop during last close
of a devfs file descriptor in devfs_close_f().  The passed in td argument
may be NULL if the close was invoked by garbage collection of open
file descriptors in pending control messages in the socket buffer of a
UNIX domain socket after it was closed.

git-svn-id: svn://svn.freebsd.org/base/stable/9@229627 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f