[stackprotector] Changed isNoopBitcast/sameNoopInput to take TargetLoweringBase instead of TargetLowering.

Both functions only use functionality from TargetLoweringBase.

rdar://13935163

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186874 91177308-0d34-0410-b5e6-96231b3b80d8