Fix some Clang-tidy modernize warnings, other minor fixes.

Fixed warnings are: modernize-use-override, modernize-use-nullptr and modernize-redundant-void-arg.

Differential revision: http://reviews.llvm.org/D14312

llvm-svn: 252087
diff --git a/llvm/lib/Transforms/Scalar/MergedLoadStoreMotion.cpp b/llvm/lib/Transforms/Scalar/MergedLoadStoreMotion.cpp
index 744ab4b..c812d61 100644
--- a/llvm/lib/Transforms/Scalar/MergedLoadStoreMotion.cpp
+++ b/llvm/lib/Transforms/Scalar/MergedLoadStoreMotion.cpp
@@ -108,7 +108,7 @@
 
 public:
   static char ID; // Pass identification, replacement for typeid
-  explicit MergedLoadStoreMotion(void)
+  MergedLoadStoreMotion()
       : FunctionPass(ID), MD(nullptr), MagicCompileTimeControl(250) {
     initializeMergedLoadStoreMotionPass(*PassRegistry::getPassRegistry());
   }
@@ -159,7 +159,7 @@
 };
 
 char MergedLoadStoreMotion::ID = 0;
-}
+} // anonymous namespace
 
 ///
 /// \brief createMergedLoadStoreMotionPass - The public interface to this file.