It appears that under some circumstances, like virtualisiation, the

It appears that under some circumstances, like virtualisiation, the
'rdrand' instruction may occasionally not return random numbers, in
spite of looping attempts to do so. The reusult is a KASSERT/panic.

Reluctantly accept this state-of-affairs, but make a noise about it.
if this 'noise' spams the console, it may be time to discontinue
using that source.

This is written in a general way to account for /any/ source that
might not supply random numbers when required.

Submitted by:	jkh (report and slightly different fix)
Approved by:	so (/dev/random blanket)