AVX-512: Fixed compilation issue


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@201761 91177308-0d34-0410-b5e6-96231b3b80d8
AVX-512: added a lit test for truncate operation

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@201763 91177308-0d34-0410-b5e6-96231b3b80d8