Revert r216066, "Optimize ZERO_EXTEND and SIGN_EXTEND in both SelectionDAG Builder and type".



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216147 91177308-0d34-0410-b5e6-96231b3b80d8
Fix a bug around truncating vector in const prop.

In constant folding stage, "TRUNC" can't handle vector data type.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216149 91177308-0d34-0410-b5e6-96231b3b80d8