These new functions for generating pseudo numbers replace the old
macro-based approach:
coap_prng() replaces prng() to generate new pseudo random numbers.
This function uses getrandom() if HAVE_GETRANDOM is defined at
build time.
coap_prng_init() replaces prng_init() to seed the pseudo random
number generator. The function does nothing if HAVE_GETRANDOM is
set at build time.
coap_set_prng() can be used to register a custom pseudo number
generation function replacing the default.
Olaf Bergmann
f17112659e