GN Build fixes for Flutter + gen_snapshot fix

runtime/bin/BUILD.gn

 # Copyright (c) 2014, 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.
 
 
 declare_args() {
   dart_io_support = false
 }
 
 
@@ skipping 154 matching lines @@
     "..",
   ]
 
   defines = [
     "DART_SHARED_LIB",
   ]
 }
 
 
 executable("gen_snapshot") {
-  configs += ["..:dart_config"]
+  configs += ["..:dart_config", "..:dart_gen_snapshot_config"]
   deps = [
     ":gen_resources_cc",
     ":gen_snapshot_dart_io",
     ":generate_builtin_cc_file",
     ":generate_io_cc_file",
     ":generate_io_patch_cc_file",
     ":libdart_builtin",
     ":libdart_nosnapshot",
   ]
 
@@ skipping 115 matching lines @@
     "log_macos.cc",
     "log_win.cc",
     "log.h",
   ]
 
   include_dirs = [
     "..",
     "//third_party"
   ]
 }