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

tools/gn/filesystem_utils.cc

 // 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.
 
 #include "tools/gn/filesystem_utils.h"
 
 #include <algorithm>
 
 #include "base/file_util.h"
 #include "base/logging.h"
@@ skipping 213 matching lines @@
         case Target::SHARED_LIBRARY:
           return "dll.lib";  // Extension of import library.
         case Target::STATIC_LIBRARY:
           return "lib";
         default:
           NOTREACHED();
       }
       break;
 
     case Settings::LINUX:
+    case Settings::FREEBSD:
       switch (type) {
         case Target::EXECUTABLE:
           return "";
         case Target::SHARED_LIBRARY:
           return "so";
         case Target::STATIC_LIBRARY:
           return "a";
         default:
           NOTREACHED();
       }
@@ skipping 486 matching lines @@
   return GetGenDirForSourceDir(target->settings(), target->label().dir());
 }
 
 SourceDir GetCurrentOutputDir(const Scope* scope) {
   return GetOutputDirForSourceDir(scope->settings(), scope->GetSourceDir());
 }
 
 SourceDir GetCurrentGenDir(const Scope* scope) {
   return GetGenDirForSourceDir(scope->settings(), scope->GetSourceDir());
 }