ic-dummy-getrandom-for-wasm

The rand crate is widely used in the Rust ecosystem. The rand crate in turn relies on getrandom to acquire cryptographic seed material. For policy reasons, getrandom refuses to compile on the wasm32-unknown-unknown target used by the Internet Computer. This prevents using rand without workarounds.

This crate implements such a workaround; on wasm32-unknown-unknown target, it registers a custom getrandom implementation which just returns an error at runtime. On any other target, it does nothing.