Function wasm_runtime_spawn_exec_env

pub unsafe extern "C" fn wasm_runtime_spawn_exec_env(
    exec_env: wasm_exec_env_t,
) -> wasm_exec_env_t

Spawn a new exec_env, the spawned exec_env can be used in other threads

@param num the original exec_env

@return the spawned exec_env if success, NULL otherwise