[GN]: Fix bug where cflag vars were not being written on non-PCH builds

tools/gn/variables.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_VARIABLES_H_
 #define TOOLS_GN_VARIABLES_H_
 
 #include <map>
 
 #include "base/strings/string_piece.h"
@@ skipping 85 matching lines @@
 extern const char* kCflagsCC_Help;
 
 extern const char kCflagsObjC[];
 extern const char kCflagsObjC_HelpShort[];
 extern const char* kCflagsObjC_Help;
 
 extern const char kCflagsObjCC[];
 extern const char kCflagsObjCC_HelpShort[];
 extern const char* kCflagsObjCC_Help;
 
-extern const char kCflagsPCHC[];
-extern const char kCflagsPCHC_HelpShort[];
-extern const char* kCflagsPCHC_Help;
-
-extern const char kCflagsPCHCC[];
-extern const char kCflagsPCHCC_HelpShort[];
-extern const char* kCflagsPCHCC_Help;
-
-extern const char kCflagsPCHObjC[];
-extern const char kCflagsPCHObjC_HelpShort[];
-extern const char* kCflagsPCHObjC_Help;
-
-extern const char kCflagsPCHObjCC[];
-extern const char kCflagsPCHObjCC_HelpShort[];
-extern const char* kCflagsPCHObjCC_Help;
-
 extern const char kCheckIncludes[];
 extern const char kCheckIncludes_HelpShort[];
 extern const char kCheckIncludes_Help[];
 
 extern const char kCompleteStaticLib[];
 extern const char kCompleteStaticLib_HelpShort[];
 extern const char kCompleteStaticLib_Help[];
 
 extern const char kConfigs[];
 extern const char kConfigs_HelpShort[];
@@ skipping 108 matching lines @@
 // Note: this is used only for help so this getter is not threadsafe.
 const VariableInfoMap& GetBuiltinVariables();
 
 // Returns the variables used by target generators.
 // Note: this is used only for help so this getter is not threadsafe.
 const VariableInfoMap& GetTargetVariables();
 
 }  // namespace variables
 
 #endif  // TOOLS_GN_VARIABLES_H_