planckdz

Add jitter entropy to the System RNG (BOTAN_TARGET_OS_HAS_CCRANDOM)

1

Add [jitterentropy-library](https://github.com/smuellerDD/jitterentropy-library) to Botan as a module. When enabled, the system RNG can use this additional entropy and depends on jitterentropy-library. So far I have implemented this only for `BOTAN_TARGET_OS_HAS_CCRANDOM`...