Pull up following revision(s) (requested by maxv in ticket #1916):
	sys/compat/linux32/common/linux32_socketcall.c: revision 1.9
	sys/compat/linux/common/linux_socketcall.c: revision 1.44
If SCARG(uap, what) = 0, copyin() will copy (size_t)-1 bytes, and it's not
a good idea; but not proven harmful.
With the help of njoly@
Ticket 1916.