[DAGCombiner] revert r295336

r295336 causes a bootstrapped clang to fail for many compilations on
powerpc BE.  See 
http://lab.llvm.org:8011/builders/clang-ppc64be-linux-multistage/builds/2315
for example.

Reverting as per the developer's request.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@295849 91177308-0d34-0410-b5e6-96231b3b80d8
9 files changed