[AST][NFC] Pack CXXDefaultInitExpr

Use the newly available space in the bit-fields of Stmt.
This saves one pointer per CXXDefaultInitExpr.

llvm-svn: 347138
diff --git a/clang/lib/Serialization/ASTReaderStmt.cpp b/clang/lib/Serialization/ASTReaderStmt.cpp
index cf39ccc..db790c5 100644
--- a/clang/lib/Serialization/ASTReaderStmt.cpp
+++ b/clang/lib/Serialization/ASTReaderStmt.cpp
@@ -1487,7 +1487,7 @@
 void ASTStmtReader::VisitCXXDefaultInitExpr(CXXDefaultInitExpr *E) {
   VisitExpr(E);
   E->Field = ReadDeclAs<FieldDecl>();
-  E->Loc = ReadSourceLocation();
+  E->CXXDefaultInitExprBits.Loc = ReadSourceLocation();
 }
 
 void ASTStmtReader::VisitCXXBindTemporaryExpr(CXXBindTemporaryExpr *E) {