use getrandom() and getentropy() since wasm and probably other platforms use them for std::random_device?

[Jonathan Wakely]

On Thu, 4 Nov 2021 at 01:16, sotrdg sotrdg via Libstdc++ <
libstdc++@gcc.gnu.org> wrote:

>
> llvm-project/random.cpp at main · llvm/llvm-project (github.com)<
> https://github.com/llvm/llvm-project/blob/main/libcxx/src/random.cpp>
>
> libcxx uses them
>


Supporting getentropy in random_device seems reasonable.