Upgrade x86_64-fortanix-unknown-sgx platform support to tier 2#57130

Merged

bors merged 2 commits intorust-lang:masterfrom VardhanThigle:Vardhan/x86_64-fortanix-unknown-sgx-tier2_support

Jan 15, 2019

+134-20

Commits on Jan 13, 2019

Adding Build automation for x86_64-fortanix-unknown-sgx
Vardhan Thigle
committed
Fix breakage from rust-lang#56988 and workaround for rust-lang#57569
Vardhan Thigle
committed