Apply modernize-use-default to clang.

Summary: Replace empty bodies of default constructors and destructors with '= default'.

Reviewers: bkramer, klimek

Subscribers: klimek, alexfh, cfe-commits

Differential Revision: http://reviews.llvm.org/D13890

llvm-svn: 250822
diff --git a/clang/lib/Lex/HeaderSearch.cpp b/clang/lib/Lex/HeaderSearch.cpp
index 469d782..79564ca 100644
--- a/clang/lib/Lex/HeaderSearch.cpp
+++ b/clang/lib/Lex/HeaderSearch.cpp
@@ -50,7 +50,7 @@
   return ControllingMacro;
 }
 
-ExternalHeaderFileInfoSource::~ExternalHeaderFileInfoSource() {}
+ExternalHeaderFileInfoSource::~ExternalHeaderFileInfoSource() = default;
 
 HeaderSearch::HeaderSearch(IntrusiveRefCntPtr<HeaderSearchOptions> HSOpts,
                            SourceManager &SourceMgr, DiagnosticsEngine &Diags,