Allow the bootstrap binary of GN (the one in TEMPDIR) to build and run on FreeBSD.

tools/gn/settings.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_SETTINGS_H_
 #define TOOLS_GN_SETTINGS_H_
 
 #include "base/files/file_path.h"
 #include "tools/gn/build_settings.h"
 #include "tools/gn/import_manager.h"
@@ skipping 10 matching lines @@
 // use it from multiple threads during target generation without locking (which
 // is important, because it gets used a lot).
 //
 // The Toolchain object holds the set of stuff that is set by the toolchain
 // declaration, which obviously needs to be set later when we actually parse
 // the file with the toolchain declaration in it.
 class Settings {
  public:
   enum TargetOS {
     UNKNOWN,
+    FREEBSD,
     LINUX,
     MAC,
     WIN
   };
 
   // Constructs a toolchain settings. The output_subdir_name is the name we
   // should use for the subdirectory in the build output directory for this
   // toolchain's outputs. It should have no slashes in it. The default
   // toolchain should use an empty string.
   Settings(const BuildSettings* build_settings,
@@ skipping 12 matching lines @@
     default_toolchain_label_ = default_label;
   }
 
   // Indicates if this corresponds to the default toolchain.
   bool is_default() const {
     return toolchain_label_ == default_toolchain_label_;
   }
 
   bool IsMac() const { return target_os_ == MAC; }
   bool IsLinux() const { return target_os_ == LINUX; }
+  bool IsFreeBSD() const { return target_os_ == FREEBSD; }
   bool IsWin() const { return target_os_ == WIN; }
 
   TargetOS target_os() const { return target_os_; }
   void set_target_os(TargetOS t) { target_os_ = t; }
 
   const OutputFile& toolchain_output_subdir() const {
     return toolchain_output_subdir_;
   }
   const SourceDir& toolchain_output_dir() const {
     return toolchain_output_dir_;
@@ skipping 47 matching lines @@
   SourceDir toolchain_gen_dir_;
 
   Scope base_config_;
 
   bool greedy_target_generation_;
 
   DISALLOW_COPY_AND_ASSIGN(Settings);
 };
 
 #endif  // TOOLS_GN_SETTINGS_H_