We no longer block indefinitely -- if nothing else, the hardclock
timer should yield enough samples to unblock /dev/random on all but
the most severely deterministic machines -- so it should be generally
safe for availability to set entropy=wait.
This doesn't guarantee that HWRNG/seed has been provided before you
run ssh-keygen or call getentropy(3) in a user application, but it
does raise the security above netbsd<=9.
PR security/55659
PR lib/56905
XXX pullup-10
e857694c31