xen: periodically refeed entropy, the same as the Unix implementation
xen: periodically refeed entropy, the same as the Unix implementation

It's now a fatal error to fail to read the host entropy device, if one has
been configured.

Signed-off-by: David Scott <63c9eb0ea83039690fefa11afe17873ba8278a56@eu.citrix.com>

mirage/mirage-entropy,mirage/mirage-entropy