Fix Clang-tidy modernize-use-override warnings, other minor fixes.

Differential revision: http://reviews.llvm.org/D14310

llvm-svn: 252034
diff --git a/lld/lib/ReaderWriter/MachO/SectCreateFile.h b/lld/lib/ReaderWriter/MachO/SectCreateFile.h
index ea16e69..2e6e97c 100644
--- a/lld/lib/ReaderWriter/MachO/SectCreateFile.h
+++ b/lld/lib/ReaderWriter/MachO/SectCreateFile.h
@@ -23,7 +23,6 @@
 //
 class SectCreateFile : public File {
 public:
-
   class SectCreateAtom : public SimpleDefinedAtom {
   public:
     SectCreateAtom(const File &file, StringRef segName, StringRef sectName,
@@ -68,19 +67,19 @@
       new (allocator()) SectCreateAtom(*this, seg, sect, std::move(content)));
   }
 
-  const AtomVector<DefinedAtom> &defined() const {
+  const AtomVector<DefinedAtom> &defined() const override {
     return _definedAtoms;
   }
 
-  const AtomVector<UndefinedAtom> &undefined() const {
+  const AtomVector<UndefinedAtom> &undefined() const override {
     return _noUndefinedAtoms;
   }
 
-  const AtomVector<SharedLibraryAtom> &sharedLibrary() const {
+  const AtomVector<SharedLibraryAtom> &sharedLibrary() const override {
     return _noSharedLibraryAtoms;
   }
 
-  const AtomVector<AbsoluteAtom> &absolute() const {
+  const AtomVector<AbsoluteAtom> &absolute() const override {
     return _noAbsoluteAtoms;
   }