Add a const and munge some comments

llvm-svn: 216781
diff --git a/llvm/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp b/llvm/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp
index 6570e14..ff8d3ad 100644
--- a/llvm/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp
@@ -148,7 +148,7 @@
 
       // If we have a musttail call in a variadic funciton, we need to ensure we
       // forward implicit register parameters.
-      if (auto *CI = dyn_cast<CallInst>(I)) {
+      if (const auto *CI = dyn_cast<CallInst>(I)) {
         if (CI->isMustTailCall() && Fn->isVarArg())
           MF->getFrameInfo()->setHasMustTailInVarArgFunc(true);
       }