DAG: Remove unused TargetLowering field (llvm#164969)

This has been dead since 97bfb93

Author: arsenm

llvm/include/llvm/CodeGen/TargetLowering.h

@@ -3813,10 +3813,6 @@ class LLVM_ABI TargetLoweringBase {
   /// The list of libcalls that the target will use.
   RTLIB::RuntimeLibcallsInfo Libcalls;
 
-  /// The ISD::CondCode that should be used to test the result of each of the
-  /// comparison libcall against zero.
-  ISD::CondCode CmpLibcallCCs[RTLIB::UNKNOWN_LIBCALL];
-
   /// The bits of IndexedModeActions used to store the legalisation actions
   /// We store the data as   | ML | MS |  L |  S | each taking 4 bits.
   enum IndexedModeActionsBits {