Documentation cleanup: escape a < character in a Doxygen comment

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@158861 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/clang/Lex/HeaderSearch.h b/include/clang/Lex/HeaderSearch.h
index 60d46f5..904d643 100644
--- a/include/clang/Lex/HeaderSearch.h
+++ b/include/clang/Lex/HeaderSearch.h
@@ -306,7 +306,7 @@
   /// already known.
   void setTarget(const TargetInfo &Target);
   
-  /// \brief Given a "foo" or <foo> reference, look up the indicated file,
+  /// \brief Given a "foo" or \<foo> reference, look up the indicated file,
   /// return null on failure.
   ///
   /// \returns If successful, this returns 'UsedDir', the DirectoryLookup member