Fix tabs

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205648 91177308-0d34-0410-b5e6-96231b3b80d8
Add DAG parameter to ComputeNumSignBitsForTargetNode

This way, you can check the number of sign bits in the
operands. The depth parameter it already has is pretty useless
without this.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205649 91177308-0d34-0410-b5e6-96231b3b80d8