Revert "[InstCombine] Optimize redundant 'signed truncation check pattern'."

At least one buildbot was able to actually trigger that assert
on the top of the function. Will investigate.

This reverts commit r339610.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@339612 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed