Revert "[ThinLTO] Use MD5 hash in function index." due to bot failure

This reverts commit r260408. Bot failure that I need to investigate.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@260412 91177308-0d34-0410-b5e6-96231b3b80d8
14 files changed