Make list_files.py and list_dart_files.py return absolute paths for GN

runtime/vm/vm.gypi

 # 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.
 
 {
   'variables': {
     'gen_source_dir': '<(SHARED_INTERMEDIATE_DIR)',
     'libgen_in_cc_file': '../lib/libgen_in.cc',
     'builtin_in_cc_file': '../bin/builtin_in.cc',
     'async_cc_file': '<(gen_source_dir)/async_gen.cc',
@@ skipping 1243 matching lines @@
         'generate_isolate_library_patch',
         'generate_math_library_patch',
         'generate_mirrors_library_patch',
         'generate_profiler_library_patch',
         'generate_vmservice_library_patch',
       ],
       'actions': [
         {
           'action_name': 'patch_sdk',
           'inputs': [
-            '<!@(["python", "../tools/list_files.py",' '"dart$",' '"sdk/lib"])',
+            '<!@(["python", "../tools/list_files.py", "relative",'
+                  '"dart$", "sdk/lib"])',
             '../../tools/patch_sdk.py',
             '../../tools/patch_sdk.dart',
             # Unlike the other libraries in the SDK, dart:typed_data is not
             # implemented as a patch applied to the base SDK implementation.
             # Instead the VM has a complete replacement library and the
             # implementation in the SDK is ignored.
             '../lib/typed_data.dart',
             # Unlike the other libraries in the SDK, dart:_builtin and
             # dart:nativewrappers are only available for the Dart VM.
             '../bin/builtin.dart',
@@ skipping 409 matching lines @@
             '--output',
             '<(gen_source_dir)/patches/<(library_name)_patch.dart',
             '<@(_sources)',
           ],
           'message': 'Generating <(library_uri) patch.',
         },
       ],
     },
   ]
 }