[PATCH] Remove os_random() and refactor its callers to use os_get_random(...)

[Nick Lowe]

Because it is a relatively insignificant factor for the quantity of
random bits that are being consumed in insensitive areas, where
os_random suffices, compared to everything else.

/dev/urandom isn't so CPU heavy that it is tangible for the use cases
and it stops a future changes using what can be a dangerous function.

I agree there are places where os_random could remain, but it just
isn't worth it for no tangible benefit.