Ban passing of kqueue descriptors via UNIX domain sockets.  Currently, they're tightly bound to struct filedesc, leading to NULL derefs during exit1().
Ban passing of kqueue descriptors via UNIX domain sockets.  Currently,
they're tightly bound to struct filedesc, leading to NULL derefs
during exit1().

ok henning@, millert@, kettenis@

orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars