[LLDB][NativePDB] Fix a minor bug.

llvm::codeview::visitMemberRecordStream in CompleteTagDecl will call
GetOrCreateType create type if not seen before, which inserts new entries
into m_decl_to_status. This may invalidates status which is a reference to
std::pair::second from DenseMapIterator.

lldb/source/Plugins/SymbolFile/NativePDB/PdbAstBuilder.cpp

@@ -776,7 +776,7 @@ bool PdbAstBuilder::CompleteTagDecl(clang::TagDecl &tag) {
       llvm::codeview::visitMemberRecordStream(field_list.Data, completer);
   completer.complete();
 
-  status.resolved = true;
+  m_decl_to_status[&tag].resolved = true;
   if (error) {
     llvm::consumeError(std::move(error));
     return false;