Serialize InitListExpr's initializesStdInitializerList bit, so it's not left uninitialized.

Found by valgrind.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@151527 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Serialization/ASTWriterStmt.cpp b/lib/Serialization/ASTWriterStmt.cpp
index f9c3c5d..4f766d9 100644
--- a/lib/Serialization/ASTWriterStmt.cpp
+++ b/lib/Serialization/ASTWriterStmt.cpp
@@ -598,6 +598,7 @@
   else
     Writer.AddDeclRef(E->getInitializedFieldInUnion(), Record);
   Record.push_back(E->hadArrayRangeDesignator());
+  Record.push_back(E->initializesStdInitializerList());
   Record.push_back(E->getNumInits());
   if (isArrayFiller) {
     // ArrayFiller may have filled "holes" due to designated initializer.