If we have arch_get_random_seed*(), try to use it for emergency refill
of the entropy pool before giving up and blocking on /dev/random.  It
may or may not work in the moment, but if it does work, it will give
the user better service than blocking will.
Reviewed-by: NIngo Molnar <mingo@kernel.org>
Signed-off-by: NH. Peter Anvin <hpa@linux.intel.com>
Signed-off-by: NTheodore Ts'o <tytso@mit.edu>