GlobalISel: rename legalizer components to match others.

The previous names were both misleading (the MachineLegalizer actually
contained the info tables) and inconsistent with the selector & translator (in
having a "Machine") prefix. This should make everything sensible again.

The only functional change is the name of a couple of command-line options.

llvm-svn: 284287
diff --git a/llvm/include/llvm/Target/TargetSubtargetInfo.h b/llvm/include/llvm/Target/TargetSubtargetInfo.h
index 47f74b0..c5585c3 100644
--- a/llvm/include/llvm/Target/TargetSubtargetInfo.h
+++ b/llvm/include/llvm/Target/TargetSubtargetInfo.h
@@ -26,9 +26,9 @@
 class CallLowering;
 class DataLayout;
 class InstructionSelector;
+class LegalizerInfo;
 class MachineFunction;
 class MachineInstr;
-class MachineLegalizer;
 class RegisterBankInfo;
 class SDep;
 class SUnit;
@@ -107,9 +107,7 @@
     return nullptr;
   }
 
-  virtual const MachineLegalizer *getMachineLegalizer() const {
-    return nullptr;
-  }
+  virtual const LegalizerInfo *getLegalizerInfo() const { return nullptr; }
 
   /// getRegisterInfo - If register information is available, return it.  If
   /// not, return null.