[SystemZ] Add a wrapping with #ifndef NDEBUG to silence warning.

SystemZHazardRecognizer::TII is only used for debug output, so it needs
also to be wrapped with #ifndef NDEBUG.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@311074 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/SystemZ/SystemZHazardRecognizer.h

@@ -45,7 +45,9 @@ namespace llvm {
 /// SystemZHazardRecognizer maintains the state for one MBB during scheduling.
 class SystemZHazardRecognizer : public ScheduleHazardRecognizer {
 
+#ifndef NDEBUG
   const SystemZInstrInfo *TII;
+#endif
   const TargetSchedModel *SchedModel;
 
   /// Keep track of the number of decoder slots used in the current