Add jitterentropy-rngd, a tool similar to rng-tools.
While not necessarily needed, it is useful for those
who want to strengthen their kernel entropy input pool
by periodic insertion of an independent source.
The entropy source is a NIST SP800-90B compliant
non-physical true RNG source on most systems.
See the jitterentropy documentation for details
(http://chronox.de/jent/doc/CPU-Jitter-NPTRNG.pdf).
Signed-off-by: Markus Theil <theil.markus@gmail.com>