GN: Don't generate phony rules called "all".

tools/gn/ninja_build_writer.h

 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef TOOLS_GN_NINJA_BUILD_WRITER_H_
 #define TOOLS_GN_NINJA_BUILD_WRITER_H_
 
 #include <iosfwd>
+#include <set>
 #include <vector>
 
 #include "tools/gn/path_output.h"
 
 class BuildSettings;
 class Err;
 class Settings;
 class Target;
 class Toolchain;
 
@@ skipping 18 matching lines @@
                    std::ostream& dep_out);
   ~NinjaBuildWriter();
 
   bool Run(Err* err);
 
   void WriteNinjaRules();
   void WriteLinkPool();
   void WriteSubninjas();
   bool WritePhonyAndAllRules(Err* err);
 
-  void WritePhonyRule(const Target* target, const OutputFile& target_file,
-                      const std::string& phony_name);
+  // Writes a phony rule for the given target with the given name. Adds the new
+  // name to the given set. If the name is already in the set, does nothing.
+  void WritePhonyRule(const Target* target,
+                      const OutputFile& target_file,
+                      const std::string& phony_name,
+                      std::set<std::string>* written_rules);
 
   const BuildSettings* build_settings_;
   std::vector<const Settings*> all_settings_;
   const Toolchain* default_toolchain_;
   std::vector<const Target*> default_toolchain_targets_;
   std::ostream& out_;
   std::ostream& dep_out_;
   PathOutput path_output_;
 
   DISALLOW_COPY_AND_ASSIGN(NinjaBuildWriter);
 };
 
 #endif  // TOOLS_GN_NINJA_BUILD_WRITER_H_