Revert my previous patch to make the valgrind bots happy.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121461 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/tools/lto/LTOCodeGenerator.cpp b/tools/lto/LTOCodeGenerator.cpp
index d49e6a7..f1c5680 100644
--- a/tools/lto/LTOCodeGenerator.cpp
+++ b/tools/lto/LTOCodeGenerator.cpp
@@ -347,7 +347,7 @@
 
   // mark which symbols can not be internalized 
   if (!_mustPreserveSymbols.empty()) {
-    MCContext Context(*_target->getMCAsmInfo(), NULL);
+    MCContext Context(*_target->getMCAsmInfo());
     Mangler mangler(Context, *_target->getTargetData());
     std::vector<const char*> mustPreserveList;
     for (Module::iterator f = mergedModule->begin(),