Move most of the shared random functions that are needed outside of the
dirauth module.
At this commit, because dirvote.c hasn't been refactor, it doesn't compile
because some SR functions need a dirvote function.
Furthermore, 5 functions haven't been touched yet because they are dirauth
only but are in used in other C files than the dirauth module ones.
No code behavior change. Only moving code around.
Signed-off-by: David Goulet <dgoulet@torproject.org>
