Removes const qualification for two methods in TargetDataLowering.

Removes const qualifier for TargetDataLowering::lowerGlobals() and TargetDataLowering::lowerConstants()

BUG= None
R=stichnot@chromium.org

Review URL: https://codereview.chromium.org/1177873003.
diff --git a/src/IceTargetLowering.h b/src/IceTargetLowering.h
index 069b49e..66e663b 100644
--- a/src/IceTargetLowering.h
+++ b/src/IceTargetLowering.h
@@ -380,9 +380,8 @@
   static std::unique_ptr<TargetDataLowering> createLowering(GlobalContext *Ctx);
   virtual ~TargetDataLowering();
 
-  virtual void
-  lowerGlobals(std::unique_ptr<VariableDeclarationList> Vars) const = 0;
-  virtual void lowerConstants() const = 0;
+  virtual void lowerGlobals(std::unique_ptr<VariableDeclarationList> Vars) = 0;
+  virtual void lowerConstants() = 0;
 
 protected:
   explicit TargetDataLowering(GlobalContext *Ctx) : Ctx(Ctx) {}