Use std::list so that we have a stable iterator.

I will try to avoid creating these std::strings, but for now this gets
the tests passing with libc++.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@182405 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/tools/obj2yaml/coff2yaml.cpp b/tools/obj2yaml/coff2yaml.cpp
index 2a70cec..0bb3e24 100644
--- a/tools/obj2yaml/coff2yaml.cpp
+++ b/tools/obj2yaml/coff2yaml.cpp
@@ -13,6 +13,8 @@
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/YAMLTraits.h"
 
+#include <list>
+
 using namespace llvm;
 
 namespace {
@@ -24,7 +26,7 @@
   void dumpSections(unsigned numSections);
   void dumpSymbols(unsigned numSymbols);
   StringRef getHexString(ArrayRef<uint8_t> Data);
-  std::vector<std::string> Strings;
+  std::list<std::string> Strings;
 
 public:
   COFFDumper(const object::COFFObjectFile &Obj);