[GN] Add support for code signing to "create_bundle" targets.

tools/gn/command_desc.cc

Index: tools/gn/command_desc.cc
diff --git a/tools/gn/command_desc.cc b/tools/gn/command_desc.cc
index f2371e9d7cb5a8591681819956cf39309e925b4f..d1edfe487b42baadd4e1cdfac511125b1a582a93 100644
--- a/tools/gn/command_desc.cc
+++ b/tools/gn/command_desc.cc
@@ -337,7 +337,7 @@ void PrintOutputs(const Target* target, bool display_header) {
     std::vector<SourceFile> output_files;
     target->bundle_data().GetOutputsAsSourceFiles(target->settings(),
                                                   &output_files);
-    PrintFileList(output_files, "", true, false);
+    PrintFileList(output_files, std::string(), true, false);
   } else {
     const SubstitutionList& outputs = target->action_values().outputs();
     if (!outputs.required_types().empty()) {
@@ -355,7 +355,7 @@ void PrintOutputs(const Target* target, bool display_header) {
     std::vector<SourceFile> output_files;
     SubstitutionWriter::ApplyListToSources(target->settings(), outputs,
                                            target->sources(), &output_files);
-    PrintFileList(output_files, "", true, false);
+    PrintFileList(output_files, std::string(), true, false);
   }
 }