Fix order-of-evaluation bug (causing GCC buildbots to fail).

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@265598 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Serialization/ASTWriterStmt.cpp

@@ -2417,7 +2417,8 @@ void ASTWriter::WriteSubStmt(Stmt *S) {
 
   Writer.Visit(S);
   
-  SubStmtEntries[S] = Writer.Emit();
+  uint64_t Offset = Writer.Emit();
+  SubStmtEntries[S] = Offset;
 }
 
 /// \brief Flush all of the statements that have been added to the