[$] A RDRAND followup

In a recent episode, "Pitchforks for RDSEED",we learned that there was some uncertainty around whether hardware-basedrandom-number generators on x86 CPUs could fail. Since the consequences offailure in some situations (confidential-computing applications inparticular) can be catastrophic, there was some concern about this prospectand what to do about it. Since then, the situation has come a bit moreinto focus, and there would appear to be an agreed-upon plan for changes tobe made to the kernel.