Update SGX example (#1933)

.gitignore

apps/sgx/enclave/enclave_config.xml.in

apps/sgx/enclave/src/lib.rs

apps/sgx/run_model.py

docker/install/ubuntu_install_rust.sh

rust/src/runtime/array.rs

rust/src/runtime/mod.rs

rust/src/runtime/packed_func.rs

rust/src/runtime/sgx.rs

rust/src/runtime/threading.rs

src/runtime/sgx/tvm.edl

src/runtime/sgx/untrusted/sgx_module.cc