Temporarily Revert "Add basic loop fusion pass."
As it's causing some bot failures (and per request from kbarton).

This reverts commit r358543/ab70da07286e618016e78247e4a24fcb84077fda.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@358546 91177308-0d34-0410-b5e6-96231b3b80d8
4868 files changed