Refactor all instances of `typedef y x` to the C++11 `using x = y` syntax.

src/IceELFObjectWriter.h

Index: src/IceELFObjectWriter.h
diff --git a/src/IceELFObjectWriter.h b/src/IceELFObjectWriter.h
index f5ae7b8b581a8110eed38c0da53a13bccd86e9b9..c1bfb746f5cc3db6364071620ccb2878887d2792 100644
--- a/src/IceELFObjectWriter.h
+++ b/src/IceELFObjectWriter.h
@@ -97,10 +97,10 @@ private:
   bool ELF64;
 
   // All created sections, separated into different pools.
-  typedef std::vector<ELFSection *> SectionList;
-  typedef std::vector<ELFTextSection *> TextSectionList;
-  typedef std::vector<ELFDataSection *> DataSectionList;
-  typedef std::vector<ELFRelocationSection *> RelSectionList;
+  using SectionList = std::vector<ELFSection *>;
+  using TextSectionList = std::vector<ELFTextSection *>;
+  using DataSectionList = std::vector<ELFDataSection *>;
+  using RelSectionList = std::vector<ELFRelocationSection *>;
   TextSectionList TextSections;
   RelSectionList RelTextSections;
   DataSectionList DataSections;