If a port provides MICROPY_PY_URANDOM_SEED_INIT_FUNC as a source of
randomness then this will be used when urandom.seed() is called without
an argument (or with None as the argument) to seed the pRNG.
Other related changes in this commit:
- mod_urandom___init__ is changed to call seed() without arguments, instead
of explicitly passing in the result of MICROPY_PY_URANDOM_SEED_INIT_FUNC.
- mod_urandom___init__ will only ever seed the pRNG once (before it could
seed it again if imported by, eg, random and then urandom).
- The Yasmarang state is moved to the BSS for builds where the state is
guaranteed to be initialised on import of the (u)random module.
Signed-off-by: Damien George <damien@micropython.org>
Damien George