Regularize some naming to make BUILD.gn files easier to write.

runtime/bin/builtin.h

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef BIN_BUILTIN_H_
 #define BIN_BUILTIN_H_
 
 #include <stdio.h>
 #include <stdlib.h>
 
@@ skipping 43 matching lines @@
   // the file.
   static Dart_Handle GetSource(const char** source_paths, const char* uri);
 
   // Native method support.
   static Dart_NativeFunction NativeLookup(Dart_Handle name,
                                           int argument_count,
                                           bool* auto_setup_scope);
 
   static const uint8_t* NativeSymbol(Dart_NativeFunction nf);
 
-  static const char* builtin_source_paths_[];
+  static const char* _builtin_source_paths_[];
   static const char* io_source_paths_[];
   static const char* io_patch_paths_[];
 
   typedef struct {
     const char* url_;
     const char** source_paths_;
     const char* patch_url_;
     const char** patch_paths_;
     bool has_natives_;
   } builtin_lib_props;
   static builtin_lib_props builtin_libraries_[];
 
   DISALLOW_ALLOCATION();
   DISALLOW_IMPLICIT_CONSTRUCTORS(Builtin);
 };
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // BIN_BUILTIN_H_