random: Add original Jitter RNG implementation
* random/jitterentropy-base-user.h: New. * random/jitterentropy-base.c: New. * random/jitterentropy.h: New.
- Tabs and trailing white spaces removed from original source.
- Source received by mail dated Fri, 27 Jan 2017 17:52:38 +0100 from Stephan
- Signed-off-by: Werner Koch <wk@gnupg.org>