Fix std::alloc::Alloc not found The lastest Rust changes the trait to std::alloc::AllocRef. Update the docker files to support sgx 2.9.1 Remove the compilerRT dependency for rust sdk update
1. Upgrade Rust SGX SDK to v1.1.0 2. Upgrade Intel SGX SDK to v2.7.1 3. Upgrade Rust to nightly-2019-11-25