Move the subtarget dependent features from SystemZTargetMachine
down to the subtarget. Add an initialization routine to assist.

llvm-svn: 212124
diff --git a/llvm/lib/Target/SystemZ/SystemZISelLowering.h b/llvm/lib/Target/SystemZ/SystemZISelLowering.h
index d6e9679..e21b050 100644
--- a/llvm/lib/Target/SystemZ/SystemZISelLowering.h
+++ b/llvm/lib/Target/SystemZ/SystemZISelLowering.h
@@ -198,7 +198,7 @@
 
 class SystemZTargetLowering : public TargetLowering {
 public:
-  explicit SystemZTargetLowering(SystemZTargetMachine &TM);
+  explicit SystemZTargetLowering(const TargetMachine &TM);
 
   // Override TargetLowering.
   MVT getScalarShiftAmountTy(EVT LHSTy) const override {