Remove evil const_cast that's not needed anymore.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@150210 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/CGObjCMac.cpp b/lib/CodeGen/CGObjCMac.cpp
index 0ac32cc..1b95547 100644
--- a/lib/CodeGen/CGObjCMac.cpp
+++ b/lib/CodeGen/CGObjCMac.cpp
@@ -4158,9 +4158,7 @@
 llvm::Constant *CGObjCCommonMac::GetMethodVarType(const ObjCMethodDecl *D,
                                                   bool Extended) {
   std::string TypeStr;
-  if (CGM.getContext().getObjCEncodingForMethodDecl(
-                                                const_cast<ObjCMethodDecl*>(D),
-                                                    TypeStr, Extended))
+  if (CGM.getContext().getObjCEncodingForMethodDecl(D, TypeStr, Extended))
     return 0;
 
   llvm::GlobalVariable *&Entry = MethodVarTypes[TypeStr];